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REPORT 


o/  <A« 


BOARD  OF  ENGINEERS 

SEWAGE  DISPOSAL 


1o   the 


CITIES  OF  PASADENA,  SOUTH 
PASADENA  AND  ALHAMBRA 

LOS  ANGELES    COUNTY,    CALIFORNIA 


SUBMITTfiB 

MARCH  27,  1916 


REPORT 

of  the 

Board   of   Engineers,  Selvage  Disposal 

to   the   Cities   of 

Pasadena,  South  Pasadena  and  Alhambra 

Los   Angeles   County,   California 


To  the  Commissioners  of  the  Cities  of   Pasadena  and  Alhambra,  and 
the  Board  of  Trustees  of  the  City  of  South  Pasadena  : 

Gentlemen  :  — 

The  undersigned  members  of  the  Board  of  Engineers  appointed 
by  you  in  January,  1915,  to  study  the  se'wage  disposal  problem  of 
the  three  cities,  and  to  render  a  comprehensive  plan  on  the  same, 
with  estimates  of  cost,  herewith  submit  their  report. 


INDEX 

To  the  Report  of  Board  of  Engineers  Sewage  Disposal 

Page 

Introduction    o 

Selection  of  Process  of  Treatment ^ 

Collection    System 2 

Preliminary    Treatment    - 

I mhoff  Tank  4 

Absence  of  Odors  ^ 

Sludge  and  Its  Disposal ^ 

Purification    Methods 6 

Oxidation    Methods   £ 

Broad  Irrigation  ^ 

Intermittent   Sand   Filtration 9 

Contact   Beds  ^^ 

Sprinkling  Filters  - 11 

Preliminary    Treatment    Required 1 1 

Distribution  of  Sewage  Over  Filters 12 

Under-Drainage    1^ 

Ventilation  of  Beds  - 13 

Purification   by   Sprinkling  Filters 14 

F"inal   Settling   Basins   15 

Disinfection    Methods   15 

Activated   Sludge   Process 16 

Report    20-45 

Outfall  Sewer  to  Ocean 20 

Discharge    Into    Rio    Hondo    River 25 

Purification    for    Irrigation 25 

Outfall  Sewer  to  Plant 26 

Design    27 

Estimates    28 

Comparison    of    Flows 31 

Treatment  Plant  32 

Primary  Imhofif  Tanks H 

Dosing  Tanks  35 

Sprinkling  Filters  35 

Secondary    Imhoff    Tank 38 

Loss   of   Head 38 

Sludge    Beds    38 

Estimates   of   Cost 39 

Proportioning   of   Costs 41 

Conclusions    44 

Appendix 

(1)  Agreement   Between   the   Cities 46-53 

(2)  Analyses  of  Pasadena's   Sewage 54 

(3)  General  Topographical  Map  of  Plant 

(4)  Plan  of  Preliminary  Imhoff  Tanks 

(5)  Plan  of  Sprinkling   Filter   and   Dosing  Tank 

(6)  Plan  of  Secondary  Settling  Tank 

(7)  Plan  of  Sludge  Beds 
C8)  Profile  Outfall  Sewer 
(9)  Population  Curves 

(10)  U.S.G.S.  Topographical  Map 

ni)  Topographical  Map  and  Profile  Through  Pass 

(12)  Sewer  Map  of  Three  Cities 

(13)  Compilation  of  Data 


INTRODUCTION 

One  of  the  most  important  functions  of  a  populous  com- 
munity is  the  proper  disposal  of  its  wastes,  and  the  disposal 
of  sewage  by  discharging  it  into  flowing  streams  or  into  large 
bodies  of  water,  such  as  lakes  or  oceans,  is  the  easiest  and 
most  natural  way  of  meeting  the  problem.  But  since  streams 
furnish  water  supplies  for  large  communities,  and  lakes  and 
the  ocean  shores  serve  as  sites  for  summer  resorts  and  play- 
grounds, this  problem  of  disposal  is  made  most  difficult. 

When  the  disposal  of  sewage  by  dilution  is  apt  to  contam- 
inate the  domestic  water  supply,  the  problem  becomes  one  of 
public  health,  as  the  excreta  of  man  and  animals  is  the  prin- 
cipal, original  vehicle  of  infection  and  contagion.  When  such 
contamination  is  in  evidence,  or  where  there  is  any  danger  of 
such  contamination,  sewage  treatment  is  needed.  The  dis- 
posal of  sewage  wastes  into  lakes  or  into  oceans  is  apt  to 
contaminate  food  supply,  and  in  such  instances,  treatment  is 
necessary  if  such  industries  are  to  be  continued. 

Very  often,  the  waters  into  which  sewage  wastes  are 
emptied,  although  not  used  for  domestic  water  supplies,  be- 
come ofifensive  to  sight  and  smell,  and  the  problem  then  be- 
comes largely  one  of  an  aesthetic  nature.  It  is  to  the  aesthetic 
side  of  the  problem  that  the  community  at  large  gives  it 
greatest  attention,  and  when  foul  odors  arise,  due  to  the  sew- 
age putrefying  in  conspicuous  places,  the  problem  receives 
prompt  attention.  Very  often,  however,  the  cost  of  improve- 
ment is  begrudgingly  met  and  then  only  as  a  result  of  litiga- 
tion. 


SELECTION  OF  THE  PROCESS  OF  TREAT- 
MENT:— The  selection  of  the  proper  process  of  treatment 
depends  wholly  upon  the  degree  of  purification  necessary. 
Each  community  has  its  own  conditions  which  must  be  met 
that  the  problem  may  be  solved  intelligently.  Under  certain 
favorable  conditions,  sewage  may  be  turned  into  streams  and 
lakes  without  treatment.  Again,  simple  tank  treatment  to  re- 
move the  suspended  solids  may  be  entirely  satisfactory.  On 
the  other  hand,  when  conditions  are  such  that  an  absolute  de- 
gree of  purification  is  necessary,  complete  oxidation  of  the 
organic  matter,  as  well  as  the  removal  of  all  harmful  bacteria, 
is  needed. 

COLLECTION  SYSTEM :— It  is  essential,  from  the 
standpoint  of  public  health,  that  the  waste  of  a  community  be 
collected  and  carried  to  the  point  of  disposal  with  as  little 
delay  as  possible.  In  the  case  of  sewage  purification,  it  is 
advisable  that  the  sewage  reach  the  treatment  plant  in  a  fresh 
state,  that  the  clarification  and  oxidation  may  be  carried  on 
without  offensive  odors.  It  is  not  always  possible  in  large 
cities,  owing  to  insufficient  grades  and  great  distances  of  flow, 
to  accomplish  this  result,  and  very  often,  in  such  cases,  sewage 
is  septic  or  foul  before  reaching  the  treatment  plant. 

PRELIMINARY  TREATMENT:— The  clarification  or 
partial  removal  of  suspended  solids  in  sewage  by  various  de- 
vices is  called  "the  preliminary  treatment."  As  already  stated, 
this  is  sometimes  as  far  as  the  treatment  goes,  and  attention  is 
hereby  called  to  the  incorrect  usage  of  the  term  "purification 
plant"  as  applied  to  this  treatment. 

The  first  treatment  that  sewage  receives  upon  reaching 
the  plant  is  screening.  When  tank  treatment  is  used  and  the 
sewage  is  separate,  i.e.,  purely  domestic  and  not  combined 
with  storm  water,  screens  are  sometimes  omitted.  If  used, 
they  are  usually  coarse  ones  to  remove  only  foreign  sub- 
stances, such  as  large  sticks,  roots  of  trees,  paper  and  other 
matter  which  would  clog  the  channels  or  float  through  the  tank 
without  being  retained.  Fine  screens  arc  sometimes  used  in 
place  of  tanks.  They  remove  a  large  proportion  of  the  solids 
in  suspension,  and,  in  their  proper  place,  give  good  results  and 
solve  the  problems  for  which  they  are  designed. 


The  sludge  problem,  probably  the  greatest  one  of  sewage 
treatment,  is  not  satisfactorily  solved  by  this  method.  The 
screenings,  if  allowed  to  dry  in  the  open  air,  give  out  noxious 
odors ;  incineration  means  continued  expense  for  fuel,  labor 
and  maintenance. 

Clarification,  or  a  removal  of  suspended  solids  in  tanks, 
is  efifected  by  regulating  the  flow  of  sewage  through  the  tanks 
so  that  the  velocity  is  such  as  to  favor  the  deposition  of  the 
coarser  solids.  This  clarification  is  sometimes  aided  by  the 
use  of  chemicals  and  the  process  is  then  known  as  chemical 
precipitation.  The  use  of  this  method  was  very  popular  some 
few  years  ago  in  England  and  in  some  of  the  New  England 
States,  but  today,  owing  to  the  cost  and  the  difficulty  of  hand- 
ling the  sludge,  is  very  rarely  recommended. 

Tank  treatment  usually  efifects  a  removal  of  from  40%  to 
60%  of  the  suspended  solids  by  the  ordinary  laws  of  subsi- 
dence. In  the  deposition  of  these  solids,  large  numbers  of  bac- 
teria are  carried  down  and  the  harmful,  polluting  properties 
of  the  sewage  are,  to  a  small  extent,  reduced.  The  solids, 
which  are  deposited  at  the  bottom  of  the  tanks,  are  known  as 
"sludge,"  and  are  constantly  being  decomposed  from  a  highly 
organic  matter,  by  the  action  of  the  living  bacteria  present,  to 
a  harmless  inorganic  substance.  The  products  of  this  decom- 
position are  liquid  and  gaseous  in  nature ;  the  liquids  flow  olT 
with  the  out-flowing  sewage  and  the  gases  escape  into  the  air. 

The  volume  of  this  deposited  sludge  is  constantly  reduced, 
but  there  is,  contrary  to  the  popular  idea  that  the  sludge  is 
completely  digested,  an  accumulation  which  must  be  removed 
at  intervals.  The  preliminary  tank,  therefore,  has  two  func- 
tions to  perform,  first,  the  removal  of  the  suspended  solids  or 
clarification  of  the  sewage,  and  second,  the  storage  of  the  sus- 
pended matter  or  sludge  and  its  decomposition  or  partial  di- 
gestion. 

There  are  various  tanks  in  use  today  to  accomplish  these 
results,  and  there  has  been  a  great  evolution  in  their  design 
since  they  were  first  put  in  use.  First  we  had  the  plain  set- 
tling tank,  where  the  main  idea  was  to  clarify  the  sewage  by 
the  removal  of  suspended  solids,  but  without  retaining  the 
sludge  until  decomposition  set  in.  Then  came  the  septic  tank 
where  ample  storage  capacity  was  provided  and  the  sludge  was 


allowed  to  decompose.  Both  of  these  tanks  were  shallow,  from 
four  to  twelve  feet  in  depth. 

Experience  has  taught  that,  in  order  to  secure  the  best 
results,  the  tanks  should  be  deep ;  and  that  the  fresh  sewage 
is  better  kept  separate  from  the  putrefying  or  decomposing 
sludge,  as  the  rising  gases  of  decomposition  interfere  with 
the  settling  of  the  suspended  solids. 

IMHOFF  TANK:— Dr.  Imhofif,  the  noted  German  en- 
gineer, after  several  years  study,  invented  a  tank  which  bears 
his  name.  This  tank  overcame  the  difificulties  of  the  plain 
sedimentation  and  septic  tank  treatments,  in  that  it  separated 
the  incoming  sewage  from  the  decomposing  sludge  and  its 
gaseous  products.  This  was  accomplished  by  designing  a  tank 
containing  a  sludge  compartment,  a  sedimentation  chamber 
and  a  scum  chamber,  separated  by  partition  walls,  with  open- 
ings or  slots  left  for  the  subsiding  solids. 

Gas  or  scum  chambers  are  so  arranged  that  the  gases  of 
decomposition  escape  into  the  air,  without  interfering  with 
the  fresh  sewage  within  the  sedimentation  chamber.  Particles 
of  sludge  that  may  rise  with  the  gases  are  also  confined  to  this 
chamber  and  do  not  come  in  contact  with  the  fresh  sewage, 
nor  are  they  allowed  to  escape  with  the  effluent,  as  often  oc- 
curs in  the  plain  sedimentation  or  septic  tanks. 


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ABSENCE  OF  ODORS,  CHARACTERISTIC  OF  IM- 
HOFF  TANKS: — Preponderance  of  evidence  from  many 
plants  in  this  country,  as  well  as  in  Europe,  show  that  well- 
designed  and  operated  Imhoff  tanks  are  free  from  odors.  The 
odor  of  hydrogen  sulphide,  so  characteristic  of  the  septic  tank, 
is  not  noticeable  about  the  ImhofT  tank,  and,  if  it  is  produced 
at  all,  it  is  absorbed  in  the  lower  compartments  of  the  tank 
and  does  not  reach  the  surface. 

SLUDGE  AND  ITS  DISPOSAL:— Sludge  is  tlie  solid 
matter  deposited  when  sewage  is  retained  in  a  quiescent  state 
for  sufficient  time  for  the  settling  of  the  suspended  matter.  The 
disposal  of  sludge  has  been  the  chief  perplexity  in  the  handling 
of  sewage  problems,  and  is  therefore  the  controlling  factor  in 
the  selection  of  a  process  of  clarification. 

As  has  been  previously  stated,  screening  sometimes  re- 
places sedimentation.  In  this  process  the  solid  matters  re- 
tained upon  the  screens  must  be  disposed  of  by  incineration, 
burial  or  by  dumping  at  sea.  If  incineration  is  resorted  to, 
the  screenings  are  usually  partially  dried,  either  by  pressing 
or  by  centrifugal  machines  to  remove  the  great  bulk  of  water. 
Often  the  screenings  are  mixed  with  saw-dust  or  other  absor- 
bent material  before  burning. 

Screenings,  if  allowed  to  dry  in  the  air,  give  ofif  noxious 
odors.  The  disposal  by  burial,  where  large  cities  are  con- 
cerned, requires  large  tracts  of  land  and  for  this  reason  is 
impractical. 

Different  types  of  settling  tanks  produce  sludge  of  widely 
varying  characteristics.  Plain  sedimentation  tank  sludge  is 
gray  in  color,  semi-liquid,  and  soon  becomes  offensive  with 
the  production  of  much  gas  and  foul  odors.  It  can  be  dried  by 
spreading  out  in  thin  layers  upon  drying  beds,  but  objection- 
able odors  result. 

The  volume  of  sludge  from  plain  sedimentation  is  much 
greater  than  in  either  the  septic  or  the  Imhofif  tank  treatment, 
but  less  than  that  from  chemical  precipitation  sludge.  This  is 
accounted  for  by  the  large  percentage  of  water  content  in  the 
sludge,  which,  under  ordinary  conditions,  amounts  to  some 
90%  to  95%. 

Chemical  precipitation  treatment  produces  the  greatest 
volume  of  sludge  and  greater  weight  of  solid  matter  i)er  1,000,- 


000  gallons  of  sewage  treated.  This  greater  volume  is  ex- 
plained by  the  more  complete  separation  of  the  undissolved 
matters  by  chemical  treatment,  as  well  as  by  the  addition  of 
the  precipitant  itself. 

Sludge  from  chemical  precipitation  is  not  so  offensive  as 
regards  odor  as  that  from  plain  sedimentation,  but  it  is  very 
difficult  to  dry,  and  owing  to  its  great  bulk  and  its  low  value 
as  a  fertilizer,  the  process  is  being  abandoned  and  is  now  sel- 
dom recommended. 

Septic  tank  sludge  is  black  in  color,  and,  if  well  digested, 
gives  off  very  little  odor.  Usually  such  decomposition  is  not 
complete,  and,  in  drying,  offensive  odors  are  produced,  due 
largely  to  the  hydrogen  sulphide  gas  present.  The  sludge  can 
be  dried  on  porous  beds,  if  spread  out  in  thin  layers,  but  drying- 
is  slow  and  not  so  easily  accomplished  as  in  the  other  methods. 
The  removal  of  sludge  from  septic  tanks  is  a  disagreeable 
task,  often  necessitating  the  cutting  out  of  the  tank  and  the 
withdrawal  of  the  supernatant  liquid. 

Imhoff'  tank  sludge  differs  greatly  in  character  from  sludge 
of  any  other  tank  treatment.  It  is  black  in  color,  of  a  gran- 
ular nature,  and  contains  great  quantities  of  gas.  Although 
a  larger  proportion  of  solid  matter  is  usually  present  than  in 
other  sludges,  it  flows  readily  on  account  of  the  contained  gas. 

Imhoff  tank  sludge  is  not  offensive,  and.  when  drawn  off' 
upon  porous  drying  beds  in  layers  from  six  to  twelve  inches 
in  depth,  dries  within  a  few  days  to  a  spongy,  earth-like  mass, 
free  from  odor.  It  has  a  value  as  a  fertilizer,  depending  upon 
the  percentage  of  nitrogen  and  phosphoric  acid  contained.  Its 
spongy  or  porous  nature  renders  additional  value  for  use  on 
heavy  soils.  The  sludge,  owdng  to  the  depth  of  the  tanks,  is 
much  more  uniform  and  more  completely  decomposed  than 
sludge  from  other  tank  processes.  The  compartments  are 
usually  designed  for  detention  periods  of  from  five  to  six 
months,  and,  in  that  time,  complete  anerobic  decomposition 
results. 

PURIFICATION  METHODS:— The  purification  pro- 
cesses may  be  divided  into  two  divisions:  First,  that  which 
removes  a  substantial  proportion  of  organic  matter,  both  dis- 
solved and  suspended,  and  gives  a  stable  effluent,  or  one  where 
only  a  moderate  degree  of  further  oxidation  is  necessarv  to 


render  the  effluent  wholly  stalile.  This  may  be  called  the  oxi- 
dation method.  Second,  there  is  that  which  destroys  the  bac- 
teria, especially  the  pathogenic  or  disease-producinj^  bacteria, 
but  does  not  materially  change  the  ph^'sical  properties  of  the 
sewage.     This  may  be  called  the  disinfection  method. 

When  the  effluent  from  the  treatment  is  turned  into  bodies 
of  water  that  are  not  used  for  domestic  consumption,  the  first 
of  these  methods  can  be  used  without  danger.  It  is  only  when 
such  effluent  is  apt  to  find  its  way  into  the  systems  of  man  or 
animals  that  further  precaution  is  necessary  and  disinfection 
methods  are  used.  These  can  be  used  on  crude  sewage  or  after 
preliminary  treatment,  as  well  as  after  oxidation  treatment. 
The  cost  of  such  treatment,  however,  decreases  with  the  de- 
gree of  preliminary  purification. 

OXIDATION  METHODS:— The  general  purpose  of 
purifying  sewage  is  to  convert  it  into  a  stable  state,  by  which 
is  meant  that  the  sewage  has  lost  its  power  of  producing  of- 
fensive odors,  or,  when  turned  into  a  stream,  will  not  cause 
harmful  pollution  of  the  water.  The  degree  of  stability  neces- 
sary in  any  case  will  depend  upon  a  number  of  conditions,  as, 
for  instance,  the  volume  of  water  into  which  the  effluent  is 
turned  compared  to  the  volume  of  effluent  added,  or  the 
amount  of  dissolved  oxygen  present  in  the  stream.  Each 
case  has  its  own  special  problem,  and  it  is  not  possible  to  make 
fixed  rules  in  regard  to  degree  of  stability,  without  first  con- 
sidering carefully  the  conditions  of  the  streams  where  such 
effluent  is  discharged. 

Oxidation  of  organic  matters  in  sewage  is  not  a  new  idea, 
although  an  understanding  of  the  agents  that  bring  about  such 
changes  is  a  development  of  a  comparatively  few  years.  There 
is  still  more  to  be  learned  in  this  connection. 

BROAD  IRRIGATION,  A  METHOD  OF  PURIFICA- 
TION:— Broad  irrigation,  or  the  disposal  of  sewage  by  turn- 
ing it  on  to  the  land,  is  the  most  natural  method  of  sewage 
disposal,  where  large  bodies  of  water  are  not  available.  That 
this  is  an  excellent  way  of  disposing  of  organic  wastes,  has 
been  known  for  centuries  past.  It  is  a  well  known  fact  that 
the  Chinese  and  Japanese  have  used  this  method  for  thousands 
of  years ;  that  the  practice   was  started  in   Europe  at  a  \-ery 


early  date,  and  that  today  the  sewage  of  Paris.  Berlin,  and 
many  other  cities  is  treated  in  this  manner. 

It  was  early  understood  that  oxidation  of  organic  matter 
resulted  from  filtration  of  sewage  through  soils,  but  that  this 
purification  was  brought  about  by  biological  agencies  was  not 
understood  until  later.  It  is  to  the  American  investigators 
that  the  world  is  indebted  for  its  present  knowledge  of  bac- 
terial purification,  for  with  the  organization  of  the  Massachu- 
setts State  Experiment  Station  at  Lawrence  in  1886.  for  the 
first  time  in  the  history  of  science,  engineers,  chemists  and  bi- 
ologists worked  together  toward  a  common  end. 

Experimental  filters  were  constructed  of  dififerent  ma- 
terials and  of  dififerent  size  particles,  and  sewage  from  the  city 
was  turned  on  to  them.  Those  who  witnessed  the  work  prophe- 
sied failure,  for  they  said.  "The  filters  are  certain  to  clog  in  a 
short  time,  for  the  process  is  only  one  of  mechanical  strain- 
ing." But,  to  everyone's  surprise,  the  filters  did  not  clog  but 
continued  in  operation  and  gave  forth  a  clear,  and  from  chem- 
ical and  biological  tests,  stable  and  pure  effluent. 

Further  studies  revealed  the  fact  that  the  solids  of  the 
sewage  were  not  held  back  by  the  filter  material  as  would  be 
the  case  with  a  strainer,  and  that  therefore  the  term,  "filter 
bed."  was  in  reality  a  misnomer.  How  then  was  this  purifica- 
tion brought  about?  Simply  by  the  aid  of  an  army  of  living 
micro-organisms  or  bacteria  which  attack  the  organic  matter, 
breaking  it  down  into  simpler  forms  which  are  oxidized  by  the 
air  into  harmless,  inorganic  matters. 

Under  favorable  soil  and  climatic  conditions,  farming 
represents  the  highest  type  of  purification  known.  The  effluent 
from  such  fields  is  literally  "spring  water,"  and  is  absolutely 
pure  and  free  from  harmful  properties.  All  soils,  however, 
are  not  adapted  to  sewage  farming  and  the  continued  applica- 
tion of  sewage  water  to  such  soils,  simply  clogs  them,  and  as 
the  sewage  pools,  it  becomes  foul  and  putrid.  Broad  irrigation 
requires  attention  and  continual  attention,  if  a  high  state  of 
purification  is  to  be  obtained  and  nuisances  prevented  by  the 
pooling  or  ponding  of  sewage. 

Quite  often  the  raising  of  crops  is  made  a  primary  consid- 
eration to  the  disposal  of  the  sewage,  and,  in  such  cases,  sew- 
age is  apt  to  be  bypassed,  and  in  this  way  the  pollution  of 

8 


streams  often  occurs.  And  again,  where  raw  sewage,  or  sew- 
age which  contains  harmful,  pathogenic  bacteria,  is  used  for 
irrigation,  it  is  not  advisable  to  raise  vegetables  which  may 
come  in  contact  with  the  sewage.  Although  available  evi- 
dence does  not  show  many  instances  of  such  contamination, 
still  it  is  best,  for  the  interests  of  public  health,  to  be  on  the 
safe  side. 

INTERMITTENT  SAND  FILTRATION :— Intermit- 
tent sand  filtration,  the  outcome  of  the  Massachusetts  experi- 
ments, differs  from  broad  irrigation  as  a  well  regulated  ma- 
chine differs  from  the  first  invention.  Instead  of  allowing  the 
sewage  to  flow  over  the  land,  specially  prepared  beds  of  sand 
are  carefully  under-drained,  permitting  the  sewage  to  perco- 
late through  thicknesses  of  from  four  to  eight  feet  of  aerated 
sand.  The  beds  are  not  in  continuous  operation,  but  are  inter- 
mittently dosed,  or,  in  other  words,  sewage  is  run  on  the  beds 
for  a  time  and  then  the  beds  are  allowed  to  rest.  During  this 
period  of  operation,  the  organic  matters  are  absorbed  by  the 
bacterial  jelly  which  soon  manifests  itself  on  the  small  sand 
grains.  The  period  of  rest  allows  the  beds  to  be  thoroughly 
aerated,  and  the  matters  retained  are  oxidized  as  previously 
stated.  They  are  then  carried  out  of  the  filter  with  the  next 
dose. 

Sand  filters  are  usually  very  highly  efficient,  both  for  bac- 
terial removal  and  for  stability  of  organic  matter.  Bacterial 
removal  in  a  well  operated  bed  should  be  fully  99%  ;  the  re- 
moval of  organic  matter  should  be  fully  95%,  and  is  often  as 
high  as  100%. 

The  rate  of  operation  of  these  beds  varies  widely  with 
the  strength  of  the  sewage,  the  character  and  porosity  of  the 
soil,  etc.,  but  in  general  it  may  be  said  that  the  rate  lies  be- 
tween 50,000  gallons  and  100,000  gallons  per  acre  per  day, 
against  a  figure  of  from  5,000  to  10,000  gallons  per  acre  per  day 
with  broad  irrigation. 

In  small  towns  or  cities,  where  land  can  be  had  at  reason- 
able rates  and  bodies  of  sand  are  plentiful  and  cheap,  this 
means  of  purification  of  sewage  is  ideal.  But,  in  large  cities, 
the  extensive  use  of  sand  filters  is  out  of  the  question  and 
some  other  means  of  treatment  must  be  sought. 


New  England  cities  have  been  using  sand  filters  since 
1887.  and  a  number  of  large  cities  have  extensive  beds  in  opera- 
tion at  the  present  time.  \\  orcester,  Mass.,  with  a  population 
of  166,000  is  using  seventy-four  acres  of  sand  filters.  They 
have  exhausted  their  sand  supply  and  land,  and  recent  reports 
indicate  that  they  are  about  to  install  sprinkling  filters. 

CONTACT  BEDS:— Man  is  ever  on  the  alert  for  more 
economical  methods  of  accomplishing  results,  and  necessity  is 
the  greatest  incentive  to  invention.  The  evolution  or  develop- 
ment of  sanitary  science  has  been  no  exception  to  this  rule, 
and.  when  it  was  found  that  sand  filters  were  impracticable  in 
certain  cases,  other  methods  that  would  allow  greater  rates  of 
application  were  experimented  with  and  found  satisfactory. 
The  contact  bed.  sprinkling  filter  and  the  new  method  now 
under  experimental  process,  activated  sludge,  may  be  said  to 
be  a  direct  growth  of  the  fundamental  principles  developed  in 
Lawrence,  Mass..  i.e.  that  the  purification  of  sewage  is  a  pro- 
cess of  oxidation  brought  about  by  the  aid  of  aerobic  bacteria 
in  the  presence  of  oxygen. 

Briefly  stated,  a  contact  bed  comprises  a  water-tight  basin, 
usually  made  of  concrete,  and  is  thoroughly  under-drained. 
The  beds  are  usually  four  to  five  feet  in  depth,  and  are  filled 
with  hard,  durable  rock  of  uniform  size,  the  size  depending 
upon  the  particular  case.  These  beds  are  allowed  to  fill  with 
sewage,  usually  taking  from  one  to  two  hours  ;  then  to  stand 
full  for  a  short  period,  usually  from  two  to  three  hours ;  then 
emptied  and  allowed  to  rest  from  four  to  six  hours. 

The  principles  of  the  contact  bed  are  much  more  complex 
than  those  of  the  sand  filters,  for  physical,  chemical  and  bio- 
logical changes  play  an  important  part.  The  organic  matters 
of  sewage,  coming  in  contact  with  the  bacterial  jelly  upon  the 
rock,  are  absorbed  by  the  jelly,  and  during  this  period  of  rest 
are  oxidized  by  the  oxygen  in  the  air  which  is  drawn  into  the 
filter  by  the  vacuum  created  by  a  depletion  of  the  oxygen  dur- 
ing the  full  period. 

Contact  filters  will  handle  between  400,000  and  600,000 
gallons  of  sewage  per  acre  daily,  and  give  good,  non-putresci- 
ble  or  stable  effluents. 

10 


Where  a  high  state  of  stability  is  required,  it  is  customary 
to  provide  double  contact  beds.  i.e.  two  sets  of  contact  filters, 
the  effluent  from  the  first  being  further  treated  in  the  second. 

Contact  filters  are  admirably  adapted  to  small  towns,  hos- 
pitals and  residential  installations,  but  for  large  cities  where 
land  and  broken  stone  are  considerations,  this  type  of  plant 
does  not  appear  to  have  a  great  field  of  usefulness.  As  to  the 
removal  of  bacterial  content  of  sewage,  contact  beds  are  not 
more  efficient  than  other  methods. 

SPRINKLING  FILTERS:— The  most  popular  device  at 
the  present  time  for  treatment  of  large  volumes  of  sewage  is 
the  sprinkling  filter.  The  merits  of  this  treatment  are  the  high 
rates  that  are  feasible  with  less  area,  and  the  lesser  cost  of 
construction  and  maintenance.  The  rates  at  which  sewage 
can  be  treated  and  give  a  stable  or  non-putrescible  effluent 
range  between  1,000,000  and  3,000,000  gallons  per  day.  with  a 
probable  average,  under  ordinary  conditions,  of  2,000,000  gal- 
lons. 

These  filters  consist  of  beds  of  hard,  durable  rock,  of 
uniform  size,  as  in  the  case  of  contact  beds.  The  size  of  the 
beds,  their  depth,  size  of  rock,  all  are  variable  quantities  and 
depend  upon  local  conditions,  as  the  strength  of  sewage,  de- 
gree of  purification,  etc. 

In  practice,  the  depth  of  beds  ranges  from  four  to  twelve 
feet.  Experience  seems  to  point  to  the  fact  that  stable  ef- 
fluents can  be  produced  at  greater  rates  per  unit  volume  of 
material,  as  the  depth  of  the  filter  increases,  and  therefore,  in 
most  cases,  when  sufficient  head  is  available,  the  cost  of  con- 
struction per  unit  of  volume  decreases  with  the  increase  in 
depth  of  the  filter. 

As  a  general  rule,  with  purely  domestic  sewage,  free  from 
detrimental,  industrial  wastes,  a  six  foot  filter  bed  gives  stable, 
non-putrescible  effluents. 

PRELIMINARY  TREATMENT  REQUIRED:— As  in 
the  case  of  intermittent  sand  filtration  and  contact  treatment, 
some  form  of  preparatory  treatment,  such  as  has  already 
been  outlined,  is  necessary  in  order  to  prevent  clogging  of 
filters  and  nozzles.  Fine  screens  can  be  used,  but  experience 
has  proven  that  tank  treatment  or  sedimentation  removes  sus- 
pended solids  more  economically  and  efficiently. 

11 


Septic  tanks  are  often  used  for  preliminary  treatment  be- 
fore sprinkling  filters,  but  their  septic  effluent  gives  off  objec- 
tionable odors.  It  has  been  proven  beyond  doubt  in  many 
large  plants  in  this  country  that  when  fresh  sewage  is  applied 
to  sprinkling  filters,  odors  are  not  noticeable,  and  authorities 
seem  to  agree  that  it  is  more  difficult  to  purify  septic  sewage 
by  bacterial  agencies. 

The  ImhofT  tank,  for  the  above  reasons,  has  proven  to  be 
the  best  preliminary  treatment  process,  where  sprinkling  filters 
are  resorted  to  for  final  treatment.  Sewage,  entering  the  puri- 
fication works,  is  apt  to  be  fresh,  unless  the  plant  is  at  a  great 
distance  from  the  city.  Since  the  detention  period  in  Imhoff 
tanks  is  short  (one  to  three  hours  as  against  two  to  twenty- 
four  hours  in  the  septic  tanks),  and  as  the  sewage  is  kept  sep- 
arate from  the  putrefying  sludge  and  septic  sewage  in  the 
lower  compartment  of  the  tank,  conditions  are  favorable  for 
fresh  sewage  entering  the  filters. 

DISTRIBUTION  OF  SEWAGE  OVER  FILTERS :— As 
the  name  "sprinkling  filter"  implies,  the  sewage  is  sprinkled 
over  the  rock  by  some  form  of  sprinkling  device.  In  America, 
nozzles  are  generally  used.  The  sewage  is  sprayed  or  sprinkled 
over  the  beds  in  a  thin  sheet,  vmder  a  varying  head,  usually 
between  two  and  ten  feet.  This  varying  head  gives  the  sew- 
age a  chance  to  be  distributed  more  evenly  over  the  rock  and 
therefore  a  more  uniform  purification  results.  The  variance  in 
head  is  accomplished  in  different  ways.  Usually  a  tank  is 
provided  which  allows  a  storage  for  a  short  time  of  the  effluent 
from  the  preliminary  treatment.  AMien  the  sewage  in  this 
tank  has  reached  a  certain  head,  or  has  filled  to  the  proper 
depth,  a  siphon  automatically  discharges  and  allows  the  fluid 
to  flow  out  through  the  distribution  system  under  the  beds 
and  through  the  sprinkling  nozzles.  It  is  therefore  apparent 
that,  as  the  level  in  the  dosing  tank  recedes,  the  pressure  or 
head  on  the  nozzle  diminishes.  With  a  high  head,  the  spray 
is  thrown  out  to  the  maximum  and  gradually  is  drawn  in  as 
the  water  level  lowers.  This  variance  of  head  is  often  accom- 
plished by  mechanical  devices,  which  operate  valves  giving  a 
variable  discharge. 

As  a  result  of  throwing  a  fine  spray  and  large  volumes  of 
sewage  into  the  air  above  the  surface  of  sprinkling  filters,  it 

12 


may  seem  to  the  layman  that  there  would  be  danger  of  dis- 
seminating harmful  bacteria,  and  that  conditions  prejudicial 
to  health  might  result.  Dr.  John  Robertson,  medical  ofiticer  of 
health  of  Birmingham,  England,  conducted  a  series  of  tests 
which  showed  that  during  the  summer,  the  number  of  bacteria 
in  the  air  passing  through  the  sprays  was  greater  before  than 
after  such  passage.  He  states  that  fifty  yards  away  from  the 
bed  on  the  lee  side  sometimes  one-fourth  the  number  of  organ- 
isms were  obtained,  as  compared  with  the  number  on  the 
windward  side,  fifty  or  one  hundred  yards  away.  When  the 
wind  was  strong,  he  found  that  a  certain  number  of  organisms 
were  carried  over  the  beds,  the  distance  varying  with  the 
strength  of  the  wind.  In  no  case,  Avas  he  able,  with  the  most 
delicate  tests,  to  detect  sewage  organisms  at  a  greater  distance 
than  one  hundred  yards  from  the  beds.  He  came  to  the  con- 
clusion that  any  harm  that  might  be  done  by  such  methods  of 
distribution  was  negligible. 

Experience  gained  from  the  operation  of  sewage  disposal 
plants,  and  there  are  a  large  number  in  operation  in  America, 
as  well  as  in  Europe,  points  to  the  fact  that  there  is  little  dan- 
ger of  contagion  or  ill  health  from  a  well-operated  plant.  The 
attendants  at  such  plants  very  often  live  in  close  proximity 
to  the  works  and  are  as  healthy  and  robust  as  the  average  per- 
son pursuing  other  lines  of  industry. 

UNDER  DRAINAGE:— Sprinkling  filters  should  be  well 
under-drained  to  assure  a  removal  of  the  percolating  fluids 
with  their  suspended  solids.  The  floor  system  is  usually  of 
concrete,  with  sufficient  gradient  toward  the  main  collectors 
to  insure  proper  carrying  velocities.  The  filter  is  separated 
from  the  floor  by  a  false  bottom  of  half  tile  drain  or  some  simi- 
lar scheme  to  insure  proper  capacity  and  to  facilitate  quick 
removal. 

VENTILATION  OF  BEDS :— For  the  proper  working 
of  a  sprinkling  filter  bed,  there  should  be  ready  access  of  air, 
that  oxidation  may  be  carried  on  without  interference.  Many 
of  the  first  filters  constructed  were  provided  with  ventilators 
and  movable  cowls  which  turned  with  the  wind,  and  thus  a 
forced  draft  was  created  which  was  carried  down  into  the  filter. 
But  experience  at  large  plants  has  clearly  shown  that  with  the 
coarse  rock  that  is  used  and  with  a  free  drainage  system,  suf- 

13 


ficient  air  is  drawn  down  in  the  filter  by  the  percolating  liquids, 
and  by  the  partial  vacuum  created  within  the  filters,  to  prop- 
erly supply  the  needed  oxygen.  Special  ventilators  are  there- 
fore not  necessary. 

PURIFICATION  BY  SPRINKLING  FILTERS :— This 
process  is  one  wholly  of  oxidation  in  which  absorption,  bac- 
terial action  and  the  activities  of  larger  organisms  all  perform 
definite  functions.  The  suspended  solids  not  removed  by  the 
preliminary  treatment  and  the  dissolved  organic  matters  are 
retained  and  absorbed  by  the  bacterial  jelly  that  is  found 
coated  upon  the  broken  rock  of  the  sprinkling  filter,  as  in  the 
contact  beds. 

This  bacterial  jelly  coats  the  stone  from  top  to  bottom  of 
the  bed  when  in  a  mature  condition.  The  organic  matters  that 
manage  to  pass  the  upper  layers  are  caught  by  those  beneath, 
and,  when  the  sewage  reaches  the  under-drains,  it  has  received 
a  high  state  of  oxidation. 

The  process  is  similar  to  that  of  the  contact  bed,  with  the 
exception  that  it  is  one  completeh^  of  oxidation,  and  not  one 
of  reduction  and  oxidation.  The  oxygen  of  the  air  being  pres- 
ent within  the  sprinkling  filter  at  all  times,  while  in  the  con- 
tact bed  during  the  full  state,  anerobic  decomposition  is  often 
produced,  which  takes  place  only  in  the  absence  of  oxygen. 

The  organic  matters  are  broken  down  into  humus-like 
material ;  carbon  dioxide  and  other  soluble  and  gaseous  prod- 
ucts are  given  ofif.  Nitrogenous  substances  are  oxidized  with 
the  production  of  free  ammonia,  nitrites  and  nitrates. 

Knowledge  of  all  organisms  and  of  the  exact  reactions 
that  take  place  is  not  yet  complete,  but  it  has  been  definitely 
proven  that  bacteria  play  an  important  part,  as  well  as  higher 
forms  of  life,  such  as  worms,  etc.  That  the  process  is  one  of 
biological  and  not  mechanical  filtration  can  be  proven  in  many 
ways.  In  the  first  place,  the  filters  are  not  mechanical  strain- 
ers ;  they  do  not  clog  seriously  and  there  is  as  much  suspended 
solid  in  the  final  effluent  from  the  sprinkling  filters  as  enters 
the  beds.  During  the  winter  months  in  the  east,  where  the 
thermometer  usually  falls  below  zero,  bacterial  life  is  at  a  very 
low  ebb.  At  these  times  filters  retain  considerable  of  their 
humus  matter :  still  there  is  a  decided  oxidation  ot  the  effluent. 
In  the  spring  as  the  temperature  rises  and  bacterial  life  be- 

14 


comes  more  active,  these  filters  commence  to  unload  and  in 
the  summer  they  are  back  to  full  capacity. 

A<^ain,  tests  have  been  made  by  adding  germicides  to  the 
influent,  and  in  sucli  cases  it  has  been  found  that  the  organic 
matters  remain  unchanged  in  their  passage  through  the  filter. 
This  shows  that  bacterial  life  is  essential  to  the  process  of 
purification. 

In  California,  where  the  climate  is  equable  and  extreme 
differences  in  temperature  are  rare,  bacterial  activity  is  at  its 
l^est  and  should  remain  fairly  constant  throughout  the  year. 
Purification  plants  of  this  nature  should  therefore,  in  this  state, 
give  high  efficiency,  and  in  thickly  settled  communities  where 
high  rates  of  operation  are  necessary,  they  should  find  a  wide 
field  of  usefulness. 

FINAL  SETTLING  BASINS:— As  the  sprinkling  bed  is 
not  a  mechanical  strainer,  and  as  the  effluent  from  such  a  bed 
contains  practically  the  same  amount  of  solids  in  suspension  as 
when  it  left  the  preliminary  tanks,  it  is  advisable  in  most  cases 
to  provide  final  settling  tanks. 

W'hile  the  humus  matter  leaving  the  filter  has  been 
changed,  as  has  been  stated,  from  a  highly  organic  nature  to 
a  more  compact  mineral  matter,  still  it  may  contain  some  or- 
ganic matter  and  many  worms,  which,  if  allowed  to  stand  and 
dry  in  the  air,  might  produce  a  nuisance. 

Sprinkling  filter  humus  lends  itself  more  readily  to  sedi- 
mentation than  do  the  solids  in  fresh  sewage,  and  therefore 
long  periods  of  detention  in  the  tanks  are  not  necessary. 
Usually  an  hour  is  sufficient  to  remove  all  solids  capable  of 
subsiding.  A  tank  of  the  Imhoff  design  is  best  adapted  for 
this,  but  shallow  basins,  when  cleaned  often,  have  given  satis- 
factory results.  The  sludge  from  such  basins  is  not  offensive, 
and,  when  dried,  closely  resembles  garden  soil. 

DISINFECTION  METHODS:— The  primary  object  of 
sewage  purification,  as  discussed  above,  is  to  change  the  or- 
ganic matter  in  the  sewage  by  oxidation  methods  to  harmless, 
inoffensive  and  therefore  stable  and  non-putrescible  substances. 

Preliminary  purification  processes,  as  outlined,  remove  a 
large   percentage   of  the   contained   bacteria.     Still,   with   the 

15 


great  number  of  bacteria  present  in  sewage,  often  as  high  as 
20,000,000  per  cubic  centimeter,  a  removal  of  90%  would  not 
insure  safety,  if  the  remaining  10%  contained  pathogenic  spe- 
cies and  the  effluent  found  its  way  into  the  domestic  water 
supply  of  a  community.  The  object  of  disinfection  and  sterili- 
zation processes  is  to  reduce  to  a  negligible  or  absolute  degree 
the  pathogenic  germs  that  may  be  present. 

It  is  unusual  for  waters  that  receive  sewage  or  sewage 
effluents  and  are  used  for  domestic  supplies,  to  be  used  with- 
out previous  disinfection,  and  very  often  the  State  Board  of 
Health  requires  the  sewage  or  sewage  effluents  to  be  similarly 
treated. 

Many  and  various  sterilizing  and  disinfecting  agents  have 
been  employed.  Among  them  are  the  following,  acids,  heat, 
ozone,  copper  sulphate,  chlorine  and  its  compounds.  Most  of 
them  are  both  difficult  and  costly  in  application.  Chlorine  and 
its  compounds  are  the  exception,  and  in  general  these  are  the 
disinfectants  used.  The  chemicals  that  have  proven  most  prac- 
tical are  chlorine  gas,  liquid  chlorine,  calcium  hypo-chlorate 
or  common  bleaching  powder,  or  chloride  of  lime,  and  sodium 
hypo-chlorite. 

Practical  experience  has  demonstrated  that  the  greater 
number  of  pathogenic  bacteria  can  be  removed  from  crude 
sewage  or  from  effluents  from  purification  works  at  a  moder- 
ate cost.  It  is  also  true  that  the  greater  the  degree  of  prelim- 
inary treatment,  the  less  chemical  disinfectant  needed  and 
consequently  a  smaller  cost  per  million  gallons  treated. 

THE  ACTIVATED  SLUDGE  PROCESS :— The  so-called 
''new"  method  of  sewage  purification,  known  as  the  Activated 
Sludge  Process,  has  been  given  considerable  attention  during 
the  past  year,  and  more  enthusiasm  has  been  manifested  by  its 
development  than  any  other  process  since  the  Imhoff  tank. 

The  fundamental  idea  of  the  process  is  the  same  that  un- 
derlies any  of  the  other  processes  of  purification,  i.e.  that  puri- 
fication is  an  oxidation  of  the  organic  matters  of  sewage 
brought  about  by  the  aid  of  biological  agencies  and  in  the 
presence  of  oxygen.  Purification  by  aeration  is  not  a  new 
idea;  it  has  been  tried  at  various  places  in  the  past,  but  with 
little  success  until  1913  when  in  Manchester,  England,  Ed- 
ward Ardern  and  W.  T.  Lockett,  under  the  inspiration  of  Pro- 

16 


fessor  Fowler  of  the  University  of  Manchester,  carried  out  a 
set  of  experiments.  These  experiments  gave  startling  results, 
for  it  was  found  that  it  was  possible  in  the  laboratory  to  nitrify 
completely  the  sewage  of  Manchester  by  aeration  in  tanks  for 
a  period  of  five  weeks.  Many  other  investigators  in  the  past 
had  been  able  to  accomplish  similar  results,  but  this  is  as  far  as 
the  development  went.  They  reasoned  that  a  detention  period 
of  such  length  was  beyond  the  economic  limit  and  therefore 
impractical. 

Manchester  experimenters  went  one  step  further,  for  after 
five  weeks  aeration  of  the  sewage,  they  decanted,  or  drew  ofif 
the  clear  liquid,  allowing  the  sludge  to  remain.  They  then 
filled  the  tank  and  again  aerated.  It  was  found  that  the  time 
of  complete  purification  or  oxidation,  after  the  second  filling, 
was  much  shorter. 

It  was  thus  first  understood  that  the  condition  of  the 
sludge  within  the  tank  played  a  most  important  part  in  the 
process,  and  that  a  simple  injection  of  air  into  sewage  was  not 
the  only  requisite  for  purification.  An  environment  for  the 
growth  and  multiplication  of  nitrifying  bacteria  was  necessary, 
and  the  sludge,  after  becoming  non-putrescible  by  the  removal 
of  organic  matter,  oflfered  the  proper  resting  place  for  these 
bacteria,  (the  same  as  the  rock  in  the  sprinkling  filter  or  the 
sand  grain  in  the  sand  filter  in  other  processes). 

Instead  of  being  called  "Purification  by  aeration,"  the  new 
process  was  given  the  name  of  "Activated  Sludge  Process," 
owing  to  the  condition  of  the  sludge  and  the  important  part  it 
played  in  the  treatment. 

Simultaneously  with  the  experiments  carried  on  in  Man- 
chester, experiments  have  been  carried  on  in  this  country  at 
the  Massachusetts  State  Experimental  Station  at  Lawrence, 
at  the  University  of  Illinois,  in  Milwaukee,  in  Baltimore,  Md.. 
and  at  the  Hygienic  Laboratory  of  the  U.  S.  Public  Health 
Service.  The  first  experiments  were  all  carried  out  on  the  fill 
and  draw  method,  i.e.  the  tanks  were  filled  and  aerated,  and 
the  purified  liquid  withdrawn,  again  filled  and  the  process  re- 
peated. Experiments  on  a  larger  scale  are  now  being  con- 
ducted at  these  stations  on  a  continuous  flow  plan.  Whether 
or  not  this  new  process  will  supercede  the  methods  now  in  use, 
remains  to  be  seen. 


17 


It  is  certain  that  the  first  cost  of  installation  will  be  much 
lower,  but  there  are  several  unsolved  problems  upon  which 
the  future  of  the  process  depends.    They  are 

(1)  The  winter  problem. 

(2)  The  plant  supervision  problem. 

(3)  The  sludge  problem. 

(4)  The  cost  problem 

The  winter  problem,  which  would  probably  not  have  to 
be  met  in  the  West  or  Southwest,  may  prove  a  decided  stumb- 
ling block  in  climates  where  low  winter  temperatures  prevail. 
Experiments  have  shown  that  purification  is  seriously  hamp- 
ered where  the  temperature  reached  50°   Fahrenheit. 

The  problem  of  plant  supervision  promises  to  be  one  of 
great  importance,  for  in  no  process  thus  far  used  do  so  many 
determining  factors  enter.  The  sludge  tends  to  lose  its  acti- 
vated properties  very  easily,  and  the  neglect  of  any  one  of  a 
number  of  factors  such  as  air  supply,  basicity  or  alkalinity  of 
the  sewage,  percentage  of  sludge  present,  detention  period  in- 
timate mixture  of  activated  sludge  and  sewage,  and  the  distri- 
bution of  the  air  through  the  sewage,  would  hamper  the  pro- 
cess. 

The  sludge  problem  is  not  as  yet  solved;  there  are  many 
advantages  claimed  for  it  over  sludge  from  other  processes. 
It  contains  three  times  as  much  nitrogen,  twice  as  much  phos- 
phoric acid  and  one-half  as  much  fatty  matter  as  ordinary  tank 
sludge :  if  these  results  can  be  obtained  on  a  practical  engineer- 
ing scale,  the  sludge  would  have  added  value  as  a  fertilizer. 
The  percentage  of  moisture,  however,  is  high,  some  95%,  and 
the  cost  of  realizing  this  fertilizer  value  would  depend  upon 
the  cost  of  removing  this  moisture. 

THE  COST  PROBLEM: — It  seems  certain  that  the  first 
cost,  or  the  cost  of  construction,  will  be  less  in  this  process 
than  in  the  sprinkling  filter  process,  for  the  entire  treatment 
is  concentrated  in  one  plant,  while  in  the  filter  process,  prelim- 
inary clarification  tanksmustbe  considered  as  well  as  the  filters. 

The  cost  of  operation  in  the  Activated  Sludge  Process 
promises  to  be  exceedingly  high.  This  is  due  to  the  cost  of 
producing  compressed  air  and  the  amount  of  air  necessary  to 
produce  the  required  purification.    This  high  cost  of  operation 

18 


and  the  difficulties  of  the  sludge  problem  may  be  found  to 
entirely  offset  the  advantages  gained  by  the  differences  in  first 
cost  between  this  process  and  the  sprinkling  filter  process. 
But,  until  such  time  as  these  points  are  more  definitely  deter- 
mined, the  Sprinkling  Filter  Process  holds  first  place.' 


19    , 


REPORT 

In  January,  1915,  a  contract  was  entered  into  by  the  Cities 
of  Pasadena,  South  Pasadena  and  Alhambra,  a  copy  of  which 
accompanies  this  report.  Under  this  contract  the  City  En- 
gineers of  the  three  cities  were  constituted  a  Board  of  Engi- 
neers to  investigate  all  available  sites  for  disposal  works,  and 
to  prepare  plans  for  a  complete  purification  plant  capable  of 
treating  the  sewage  of  the  three  named  cities. 

The  Board  was  duly  organized  with  R.  V.  Orbison  of  Pas- 
adena as  President,  Charles  E.  Hewes  of  Alhambra  as  Secre- 
tary, and  John  MacMillan  of  South  Pasadena  as  third  member 
of  the  Board.  Immediately  upon  organization,  the  following 
methods  of  sewage  disposal  were  outlined  for  investigation : — 

(1)  An  outfall  sewer  to  the  ocean. 

(2)  A  suitable  site  and  the  construction  of  a  purification 

plant  and  disposal  of  the  effluent  of  same  into  the 
Rio  Hondo  River. 

(3)  A  location  suitably  situated,  a  treatment  plant  and 
sufficient    land    for    irrigation    by    utiUzation    of    the 

plant's  effluent. 

AN  OUTFALL  SEWER  TO  THE  OCEAN :— The  nat- 
ural drainage  of  the  three  cities  is  down  the  Rio  Hondo  River 
to  the  Los  Angeles  River,  thence  through  the  Dominguez 
Ranch  to  the  Long  Beach  Harbor.  The  San  Gabriel  River 
flows  through  level  land  north  of  El  Monte,  and  while  it 
sometimes  flows  down  the  Rio  Hondo  into  Long  Beach  harbor, 
it  usually  flows  through  another  channel  near  Whittier  and 
out  through  Alamitos  Bay. 

The  ocean  shore  between  San  Pedro  and  Alamitos  Bay 
is  well  built  up  for  the  entire  distance,  and  any  attempt  to 
establish  an  outfall  site  and  treatment  plant  along  this  stretch 
would  be  vigorously  contested  by  the  cities  and  the  property 
owners  in  that  section.  The  City  of  Los  Angeles  owns  a  strip 
a  mile  in  length  along  the  coast  at  their  outfall  site.  Yet,  with 
this  added  protection,  the  State  Board  of  Health  constantly 
receives  complaints  from  adjacent  cities. 

This  Board  believes  that,  with  existing  conditions  along 
the  coast  today,  to  establish  an  outfall  sewer  to  the  sea,  a  site 

20 


would  have  to  be  chosen  east  of  x\lamitos  Bay,  and  therefore 
in  Orange  County.  To  turn  raw  sewage  into  the  ocean  at  any 
point  on  the  coast  in  this  vicinity  is  certainly  out  of  the  ques- 
tion. Los  Angeles  City,  with  its  outfall  in  a  more  isolated 
place  than  any  site  we  might  obtain,  has  been  forced  by  the 
State  to  take  measures  for  clarification.  It  means,  therefore, 
that  even  with  an  outfall  to  the  sea,  some  process  of  clarifica- 
tion, such  as  screen  or  tank  treatment,  must  be  resorted  to. 

It  is  impossible  to  give  an  accurate  estimate  of  the  cost  of 
an  outfall  to  the  sea.  without  extensive  field  work,  but  from 
a  study  of  the  topographical  map,  we  have  been  able  to  reach 
the  following  conclusion  and  approximate  estimate. 

Supposing  it  possible  to  obtain  a  site  suitable  for  a  treat- 
ment plant  in  the  vicinity  of  Alamitos  Bay — the  distance  from 
the  southern  boundary  of  Alhambra,  for  an  outfall  sewer  fol- 
lowing county  highways  as  closely  as  possible,  is  approximate- 
ly twenty-six  miles.  Such  an  outfall  would  be  expensive  to  con- 
struct, as  well  as  to  maintain,  for  it  would  be  necessary  to  cross 
two  very  erratic  rivers  which  seemingly  change  their  course 
at  will,  sometimes  flowing  in  one  channel  and  sometimes  in 
another.  The  country  in  the  vicinity  of  Alamitos  Bay  and 
for  three  or  four  miles  inland,  is  marshy  and  therefore  level. 
Ground  water  would  be  encountered  which  would  increase 
construction  cost,  and  the  flatness  of  the  land  for  such  dis- 
tances would  add  difficulties  in  the  way  of  proper  gradients. 

Conditions  Along  Line  of  Outfall 

First  5.5  miles,  drop  in  feet  196.  a  gradient  of 67% 

2nd  7.5  miles,  drop  in  feet  100.  a  gradient  of 25% 

3rd  6.5  miles,  drop  in  feet  7S,  a  gradient  of 22% 

4th  6.5  miles,  drop  in  feet  25.  a  gradient  of 07% 

An  outfall  of  such  length  should  be  designed  for  a  future 
of  at  least  fifty  years,  and  from  a  close  study  of  past  growth 
and  an  estimate  as  to  probable  future  growth,  a  population  of 
at  least  300,000  may  be  expected  to  be  served  by  such  a  sewer. 
At  the  present  time,  the  population  of  the  three  cities  is  close 
to  60,000;  figuring  125  gallons  per  capita  per  day  as  a  max- 

211 


imum  and  safe  figure,  the  quantity  of  sewage  to  be  carried 
by  such  a  sewer  at  present  and  fifty  years  hence  would  be  as 
follows : — 

Present  Capacity  Required 

60,000  population  at  125  gallons  per  capita  daily  would  be 
equal  to  7.500,000  gallons  per  day.  Figuring  an  eighteen  hour 
period  as  the  time  in  which  the  volume  would  be  discharged, 
(the  remaining  six  hours  of  the  twenty-four  having  practically 
a  negligible  flow),  this  would  equal  a  flow  of  15.47  second  feet, 
or,  at  50  miner's  inches  to  the  second  foot,  773.50  miner's 
inches. 

Future  Capacity  Required 

300.000  population  at  125  gallons  per  capita  daily  would 
be  equal  to  37,500,000  gallons  per  day,  or  77 .Z7  second  feet,  or 
3,868.50  miner's  inches. 

Estimates  of  size  and  cost  for  future  population  of  300.000 

Size  of  Velocity  I>iii  ft.  Cost  \vx 

Grade  Pipe  of  Flow  of  Pipe  Foot  Total  Cost 

.67%  45"  7.5'  29,040  425  $123,420 

.25%  54"  5.4'  39,600  5.65  223,740 

.22%  54"  5.0'  34,320  5.65  193,908 

.07%  66"  2,.};  34,320  7.75  265,980 

$807,048 

Man  holes,  200  at  $50.  ■- ■ 10,000 

1,000  feet  cast  iron  pipe,  36",  and  800  feet  of  protection 

piling  at  outlet.  $30  per  ft. 30,000 

$847,048 
Plus   10%   engineering,   inspection,   incidentals 84,704 

$931,752 
Clarification  plant,  Imhoff  design,  to  care  for  60,000  people     75,000 

Total  $1,006,752 

This  estimate  is  exclusive  of  right-of-way  or  cost  of  land 
for  outfall  site  and  disposal  plant.  It  is  based  upon  ideal  con- 
ditions of  construction,  assuming  that  no  difficulties  would 
be  encountered  during  construction  such  as,  ground  water, 
quick  sand,  heavy  ground,  etc.,  and  that  extensive  shoring 
would  not  be  necessary. 

In  crossing  the  two  river  channels,  long  inverted  cast 
iron  siphons,  no  doubt,  would  be  needed  to  insure  permanent 

22 


construction.  The  encountering-  of  heavy  soils  and  ground 
water,  with  the  approach  to  the  ocean  shore,  would  add  ma- 
terially to  construction  cost.  It  is  therefore  safe  to  say  an 
estimate  of  20  %  to  50%  in  excess  of  the  one  given  would 
represent  more  nearly  the  cost  of  such  an  outfall. 

In  designing  sewers,  it  is  necessary  that  the  velocities  of 
flow  be  sufficient  to  carry  the  suspended  solids ;  otherwise,  de- 
posits will  form  which,  if  they  do  not  hamper  the  flow,  give 
rise  to  obnoxious  odors  due  to  the  putrefaction  of  the  organic 
matters.  Economic  considerations  usually  demand  that  an 
outfall  sewer  be  designed  for  a  period  of  years  in  the  future, 
and,  in  such  cases,  it  is  necessary  to  consider  the  actual  con- 
ditions of  operation  likely  to  occur  under  minimum  flow  dur- 
ing the  first  few  years  after  construction. 

If  velocities  are  not  sufficient,  under  minimum  flow,  to 
cleanse  the  sewer,  sufficient  water  must  be  added  at  such  times 
to  raise  the  velocities,  or  a  smaller  sewer  should  be  designed. 
The  construction  of  a  large  sewer  for  a  long  period  ahead 
would  not  be  warranted  if  the  cost  of  operation  of  such  sewer 
would  exceed  the  cost  of  construction  of  a  smaller  sewer  for 
a  short  future  and  then  building  a  second  sewer  when  the 
growth  of  the  community  warranted. 

The  normal,  or  average,  daily  flow  of  the  three  cities  today 
is  50  gallons  per  capita,  or  a  flow  of  6.19  second  feet.  The  min- 
imum flow  for  a  few  hours  each  day  may  drop  to  one  or  two 
second  feet. 

Considering  the  sewer  as  designed  for  a  future  of  fifty 
years  and  the  average  daily  flow  of  the  present,  the  conditions 
of  flow  would  be  as  follows : — 

1966  1916  Normal  Flow 

Quantity      Capacity         Velocity  .Xverace  Deptli  Velm-ity 

Grade  of  Size  of        of  Sewage     of  Sewage      of  Flow  ft.  Daily  of  of 

Sewer  Pipe  sec  ft.     Flowing  Full     iier  se<-.  Flow  Flow  Flow 

.67%  45"  TJ  82.8  7.5  6.19  8.1"  3.98 

.25%  54"  n  85.9  5.4  6.19  9.7"  2.86 

.22%  54"  n  79.5  5.0  6.19  9.7"  2.65 

.07%  66"  n  78.4  Z.Z  6.19  11.9"  1.75 

The  velocities  in  the  case  of  normal  flow  are  sufficient  for 
estimate  purposes,  although  the  1.75  feet  per  second  is  some- 
what below  what  is  deemed  good  practice,  and  during  some 
hours  of  the  day,  when  the  flow  drops  under  the  normal,  flush- 
ing would  have  to  be  resorted  to. 

23 


Your  Board  of  Engineers  believes  that,  with  the  develop- 
ment of  the  country  at  the  present  time,  where  large  tracts  of 
land  are  still  available  sufficiently  remote  from  built-up  sec- 
tions, where  the  water  problem  is  such  a  vital  consideration  to 
such  land  and  worth  anywhere  from  one  to  live  cents  per  inch 
per  hour  for  irrigation  purposes,  and  where  the  problem  is  be- 
coming more  vital  with  each  year's  growth,  to  waste  sewage 
water  when  it  is  possible  to  purify  it  for  irrigation  purposes 
in  such  a  manner  as  to  cause  no  nuisance  from  odors  or  en- 
danger public  health,  is  a  willful  waste  and  should  not  be 
tolerated. 

In  the  City  of  Alhambra.  a  city  of  3,800  acres  and  at  pres- 
ent largely  an  orchard  city,  water  for  irrigation  purposes  sells 
for  $.50  per  1,000  cu.  ft.  This  is  equivalent  to  a  rate  of  $  .036 
per  inch  per  hour.  With  a  population  of  60.000  and  a  normal 
sewage  flow  of  50  gallons  per  capita  daily,  the  daily  discharge 
is  3,000,000  gallons,  or  equivalent  to  a  constant  flow  of  approx- 
imately 310  inches.  Consider  that  no  storage  is  provided,  and 
that  it  is  possible  to  sell  water  for  only  twelve  hours  per  day 
two  hundred  days  per  year,  and  that  such  water  is  worth,  for 
irrigation  purposes,  three  cents  per  inch  per  hour 

310  inches   per  hour   at   3c $  9.30  per  hour 

12  hours  at  $9.30 111.60 

200  days  at  $111.60 22,320 

Avhich  is  equivalent  to  an  investment  of  $446,400  at  5%,  which 
is  a  little  more  interest  than  the  three  cities  will  have  to  pay 
for  forty  year  bonds  for  a  treatment  plant. 

In  ten  years,  with  a  probable  population  of  100,000  in  the 
three  cities,  the  average  daily  flow  will  be  equal  to  5,000,000 
gallons  per  day.  Using  an  eighteen  hour  period  of  flow,  this 
is  equal  to  10.32  second  feet,  or  a  constant  flow  of  516  inches. 

516  inches  per  hour  at  3c $        15.48  per  hour 

12  hours  at  $15.48 185.76 

200  days  at  $185.76 37,152.00 

which  at  5%  is  equal  to  interest  on  an  investment  of  $743,040. 

It  has  been  said  that  a  municipality  should  not  allow  com- 
mercialism to  enter  into  its  affairs.  In  some  instances  this  may 
be  true,  but  we  see  no  logic  in  any  argument  that  would  de- 
mand the  waste  of  so  valuable  an  asset,  when  such  asset  can 
be  utilized  without  interfering  with  the  rights  of  others. 

24 


THE  CONSTRUCTION  OF  A  PURIFICATION  PLANT 
AND  THE  DISCHARGE  OF  THE  EFFLUENT  FROM 
THE  SAME  INTO  THE  RIO  HONDO  RIVER. 

The  Board  investigated  this  phase  of  the  problem,  and 
found  that  undoubtedly  land  could  be  obtained  to  the  south- 
east of  Alhambra  along  the  Rio  Hondo  River.  The  discharg- 
ing of  effluent  from  a  purification  plant  into  this  river,  which 
is  a  small  stream  the  greater  part  of  the  year,  would  necessitate 
the  constant  maintenance  of  a  very  high  state  of  stability,  and. 
as  is  the  case  in  an  outfall  to  the  sea,  the  effluent  from  such 
a  plant  would  be  wasted. 

We  are  not  aware  that  this  stream  is  used  directly  for 
domestic  water  supply,  but  the  stream  feeds  the  underground 
gravels  of  the  coastal  plain,  the  water  from  which  is  pumped 
and  used  by  cities  to  the  south. 

The  river  is  also  used  for  bathing  and  its  banks  as  a  sum- 
mer resort  at  certain  times  of  the  year.  Hence,  any  pollution 
of  this  stream  would  be  out  of  the  question. 


PURIFICATION  PLANT   AND  UTILIZATION   OF  EF- 
FLUENT FOR  IRRIGATION. 

A  thorough  examination  of  all  available  land  in  the  vicin- 
ity of  Alhambra  for  the  purpose  of  the  construction  of  a  mod- 
ern purification  works  and  the  use  of  its  purified  effluent  for 
irrigation,  reveals  the  following  facts: 

On  the  west  of  Alhambra  there  is  a  range  of  hills  sepa- 
rating the  same  from  the  city  of  Los  Angeles,  but  to  find  suit- 
able land  for  such  purpose  in  this  direction  is  out  of  the  ques- 
tion. To  the  east  and  southeast  of  Alhambra  is  the  Rio  Hondo 
River,  a  small  stream  during  the  larger  part  of  the  year,  but 
a  raging  torrent  at  times  during  the  winter.  The  territory  be- 
tween the  river  and  Alhambra  is  flat  for  some  distance  back 
of  the  river,  and  the  water  plane  is  within  a  few  feet  of  the 
surface.  This  territory  is  under  cultivation,  water  for  irriga- 
tion purposes  being  pumped  from  wells  on  the  ground  or 
brought  in  from  the  Rio  Hondo  in  ditches.  Water  is  not  a  prob- 
lem in  this  section,  and  the  disposal  of  effluent  from  a  purifi- 
cation works  is  not  feasible  from  an  economic  standpoint. 

25 


To  the  south  of  Alhambra,  and  separated  by  a  long  range 
of  hills,  is  a  tract  of  several  thousand  acres  of  tillable  land  for 
which,  at  the  present  time,  water  is  unavailable.  Here  is  an 
ideal  spot  for  a  purification  works,  with  more  than  sufficient 
adjacent  land  to  utilize  the  effluent  from  such  works  for  some 
years  to  come.  The  range  of  hills  completely  shuts  ofif  the 
populated  sections  to  the  north  and  to  the  east,  and  to  the 
south  and  west  there  are  no  residences  to  speak  of  within 
three  miles. 

\\  e  notified  your  Honorable  Bodies  as  to  our  selection, 
and  after  careful  investigations,  proceedings  were  started  to 
acquire  sufficient  territory  for  a  plant  and  for  a  farm.  We 
advocated  the  purchase  of  one  thousand  acres,  for  the  reason 
that  with  the  combined  population  of  60,000,  we  would  have 
sufficient  water  to  amply  care  for  that  amount  of  land.  Owing 
to  circumstances,  however,  you  were  able  to  purchase  only  six 
hundred  acres,  but  it  is  probable  that,  in  the  near  future,  ad- 
ditional land  can  and  will  be  obtained. 

The  location  of  the  new  farm  is  shown  on  the  government 
topographical  map  accompanying  this  report  and  contains 
nearly  six  hundred  acres  of  hilly,  rolling  and  level  land.  The 
northern  boundary  of  the  farm  is  one  and  one-half  miles  from 
the  southerly  line  of  the  City  of  Alhambra. 

The  site  of  the  proposed  purification  works  is  admirably 
situated  on  the  southern  slope  of  the  roughest  part  of  the  farm, 
approximately  one-half  mile  south  of  its  northern  line,  and  on 
the  eastern  side  of  a  pass  which  extends  in  a  northerly  and 
northeasterly  direction  through  the  hills.  The  topographical 
features  of  the  proposed  purification  works  site  and  of  the 
north  central  part  of  the  farm  act  as  a  barrier  to  any  nuisance 
which  might  arise  from  odors  passing  over  into  the  country 
to  the  north. 

A  portion  of  the  farm  lying  north  of  the  proposed  plant 
is  too  high  for  irrigation  by  gravity  flow,  and  we  would  there- 
fore recommend  that  at  least  a  portion  of  this  high  land  be 
planted  to  eucalyptus  trees. 

OUTFALL  SEWER:— The  new  outfall  sewer,  a  plan 
and  profile  of  which  accompanies  this  report,  will  divert  the 
sewage  of  Pasadena,  South  Pasadena  and  a  portion  of  Alham- 
bra's,   at   the   northwest   corner   of   Pasadena's   present   farm, 

26 


thence  south  along;  the  west  Hne  of  the  farm  to  HeHman  Ave- 
nue, thence  west  on  HeUman  Avenue  to  Garfield  Avenue,  in- 
tercepting- the  major  portion  of  Alhambra's  sewerage  system  ; 
thence  south  on  Garfield  Avenue  to  Newmark  Avenue,  thence 
west  on  Newmark  Avenue  to  Ramona  Avenue,  thence  south 
on  Ramona  Avenue  to  the  south  line  of  Tract  Number  786; 
thence  in  a  general  southwesterly  direction  through  an  un- 
named pass  to  the  purification  works.  The  total  length  of 
the  sewer  is  18,400  feet,  or  3.48  miles.  The  grade  from  the  be- 
ginning to  the  south  line  of  Tract  786  is  0.286%  and  from  that 
point  to  the  plant  is  0.33%. 

DESIGN  OF  THE  OUTFALL  SEWER:— For  a  deter- 
mination of  the  proper  size  of  sewer  to  design,  it  is  necessary 
that  the  following  facts  be  known  as  nearly  as  possible : — 

(1)  Is  the  sewage  separate  or  combined? 

(2)  Population  designed  for. 

(3)  Quantity  of  sewage  to  be  taken  care  of. 

Separate  or  combined  sewage  means  whether  it  is  strictly 
domestic,  or  combined  with  storm  water.  In  this  case,  the 
sewage  is  strictly  domestic  in  character. 

The  second  feature  to  be  considered,  "Population  de- 
signed for,"  is  a  very  important  factor  and  one  incapable  of 
exact  determination.  However,  in  order  to  design  a  sewer 
for  a  period  in  the  future,  it  is  necessary  to  make  some  sort  of 
an  estimate  of  probable  future  growth.  Accompanying  this 
report  is  a  series  of  curves,  showing  the  past  growth  of  the 
three  cities  separately  and  a  curve  showing  the  combined 
growth  to  date.  From  a  study  of  the  past  growth  and  the 
growth  of  other  cities  in  the  United  States,  we  have  extended 
these  curves  and  have  reached  the  conclusions  given. 

"Quantity  of  sewage  to  be  taken  care  of"  is  also  a  factor 
indeterminate  for  a  long  period  ahead,  but  experience  has 
taught  that  with  the  growth  of  cities,  unless  some  exceptional 
changes  take  place  in  character  of  population  or  industries, 
the  water  consumption  per  capita  increases  rather  than  de- 
creases. 

In  April,  1915,  in  order  to  determine  the  sewage  flow^  of 
Pasadena,  two  Stevens  recording  gauges  were  installed,  one 
at  the  outlet  of  the  Garfield  sewer  and  one  at  the  outlet  of  the 

27 


Allen  Avenue  sewer.  After  a  period  of  one  hundred  and  fifty 
days,  by  averaging  the  daily  flow,  it  was  found  that  the  aver- 
age was  2,000,000  gallons  per  day.  Upon  a  basis  of  a  popu- 
lation of  40,000,  this  gives  an  average  flow  of  50  gallons  per 
capita  per  day.  The  maximum  rate,  according  to  these  gauges 
is  approximately  one  hundred  and  thirteen  gallons  per  capita 
daily,  and  in  our  design  we  have  used  150%  of  the  average,  or 
one  hundred  and  twenty-five  gallons  per  capita  daily  as  being 
a  safe  figure. 

Ground  Water  Entering  The  Sewer : — The  possibility  of 
any  ground  water  entering  the  sewer,  thus  increasing  the  vol- 
ume of  water  to  be  cared  for,  can  be  neglected.  The  three 
cities  are  sufificiently  high,  and  the  water  plane  so  far  beneath 
the  surface,  that  any  trouble  from  this  source  is  negligible. 

Storm  Water  Entering  The  Sewer : — The  only  access  that 
storm  water  has  to  the  sewer  is  through  the  man-hole  covers ; 
any  great  quantity  from  this  source  is  not  to  be  expected,  and 
this  phase  has  therefore  been  neglected. 


CONSIDERING  THE  SIZE,  CONDITIONS  OF  FLOW, 
AND  COST  OF  CONSTRUCTION  OF  A  SEWER  FOR 
TWENTY,    THIRTY    AND    FORTY    YEAR   FUTURE. 

Twenty  Year  Future,  or  the  Year  1936 

Probable  combined  population,  1936 146,000 

Probable  population  of  Alhambra,  1936 28,000 

All  the  sewage  of  Pasadena  and  South  Pasadena,  and  ap- 
proximately one-third  of  the  sewage  of  Alhambra,  would 
enter  the  outfall  above  the  intersection  of  Hellman  and  Gar- 
field Avenues.  The  remaining  two-thirds  of  Alhambra's  sew- 
age w^ould  enter  at  this  point. 

Gals,  per  day 
Total  maximum  flow  to  be  expected  with  a  popula- 
tion of  146,000 18,250.000 

Total  maximum  flow  to  be  expected  with  a  popula- 
tion of  28,000 3,500,000 

%  X  3,500,000  =  2,333,333  gallons  per  day  entering  sewer  at 
Hellman  and  Garfield  Avenues. 

28 


Sewer  above  Garfield  and  Hellman  Ave.,  therefore  designed 
for  18.250,000  —  2.333.333  or  15.016,666  gallons  per  day,  or 
32.84  second  feet. 

Sewer  below  Garfield  Avenue  and  Hellman  Avenue  there- 
fore designed  for  18.250.000  gallons  per  day,  or  37.65  second 
feet.  Using  brick  sewer  and  N  =  .015  (cocfiicient  of  rough- 
ness). 

(Computations   by   Slide    Rule   and   Di.scliarge    Diagrams) 


CJiado 

0.286% 
0.286% 
0.33% 

Lin.  ft.         .sig.'ied  for 
Vipe              See.  ft. 

7100        32.84 
4800        37.65 
6500        37.65 

%    engineering. 

Sine  of        of  Pipe 
Pipe            See.  ft. 

36"             32.0 

39"        37.5 
39"        41.1 

inspection   and 

FlowiuR      Unit  Cost 
Full 

4.4        $2.85 
4.7          3.30* 
5.0          3.05 

incidentals 

Total  (.'ost 

$20,235,00 
15,840.00 
19.825.00 

Plus   10 

$55,900.00 
5,590.00 

$61,490.00 

^Includes  repaying. 

Thirty  Year  Future,  or  Year  1946 

F'robable  combined  population.  1946 196,000 

Probable  population  of  Alhambra.  1946 38,000 

All  the  sewage  of  Pasadena  and  South  Pasadena  and  ap- 
proximately one-third  of  the  sewage  of  Alhambra  would  enter 
the  outfall  above  the  intersection  of  Hellman  and  Garfield 
Avenues.  The  remaining  two-thirds  of  Alhambra's  sewage 
would  enter  at  this  point. 

Gals,  per  day 
Total  maximum  fiow  to  be  expected  with  a  popula- 
tion of  196,000 24.500,000 

Total  maximum  flow  to  be  expected  with  a  popula- 
tion of  38,000 4.750,000 

^  X  4,750,000  =  3.166,666  gals,  per  day  entering  at  Hellman 
and  Garfield  Avenues. 

Sewer  above  Garfield  and  Hellman  Avenue  therefore  designed 
for  24,500,000  —  3.166.666  =  21,333.333  gals,  per  day  or  44 
second  feet. 

Sewer  below  Garfield  and  Hellman  Avenues  designed  for  24,- 
500,000  gallons  per  day  or  55.55  sec.  feet.  Using  brick 
sewer  and  N  =  .015  (coefficient  or  roughness). 

29 


Computations  by  Slide  Rule  and  Discharge  Diagrams^ 


Lin.  ft. 
Grade             Pipe 

0.286%      7100 
0.286%      4800 
0.33%        6500 

Quantity  De-                     Capacity 

signed  for       Size  of        of  Pipe 

Sec.  ft.           Pipe           Sec.  ft. 

44             42"        47.5 
50.55        45"        57.0 
50.55        45"        61.0 

neering,  inspection  and 

Velocity 

Flowing 
Full 

4.9 

5.1 

5.5 

incideni 

Unit  Cnsl 

$3.85 
4.35* 
4.10 

tals 

Total  Cost 

$27,335.00 
20,880,00 
26,650.00 

Plus  10%  engii 

$74,865.00 
7,486.00 

*Including  repaying. 


$82,351.00 


Forty  Year  Future,  or  Year  1956 

Probable  combined  population.  1956 250,000 

Probable  population  of  Alhambra,  1956 50,000 

All  the  sewage  of  Pasadena  and  South  Pasadena  and  ap- 
proximately one-third  of  the  sewage  of  Alhambra  would  enter 
the  outfall  above  the  intersection  of  Hellman  and  Garfield 
Avenues.  The  remaining  two-thirds  of  Alhambra's  sewage 
would  enter  at  this  point. 

Gals,  per  day 
Total  maximum  flow  to  be  expected  with  a  popula- 
tion of  250,000 - 31.250.000 

Total  maximum  flow  to  be  expected  from  a  popula- 
tion of  50,000 6.250,000 

Yz  X  6,250,000  =  4.166.666  gals,  per  day  entering  sewer  at  Hell- 
man  and  Garfield. 
Sewer  above  Garfield  and  Hellman  Avenues  designed  for  31.- 
250,000  —  4,166,666  or  27,083,334  gallons  per  day  or  55.88 
second  feet. 
Sewer  below  Garfield  and  Hellman  Ave.,  designed  for  31.250,- 
000  gallons  per  day.  or  64.47  second  feet.  Using  brick 
sewer  and  N  =  .015  (coefificient  of  roughness). 

(Computation  by  Slide  Rule  and  Discharge  Diagrams) 


0.286% 
0.286% 
0.33% 


Lin.  ft. 
Pipe 

Quantity  De- 
signed for 
Sec.  ft. 

Size  of 
Pipe 

Capacity 

of  Pijie 
Sec.  ft. 

Velocity 

Flowing 

Full 

Unit  Cost 

Tilt  J 1  Cost 

7100 
4800 
6500 

55.88 

64.47 
64.47 

45" 
48" 
48" 

57 

68 
72 

5.1 

5.4 
5.7 

$4.10 
4.60* 
4.30 

$29,110.00 
22,080.00 
27,950.00 

$79,140.00 
Plus  10%  engineering,  inspection  and  incidentals  7.914.00 


*Including  repaying.  $87,054.00 

30 


Comparisons  of  Flow  in  1916,  1936,  1946  and  1956 
Future  Twenty  Years 


(Juautity 

KlottiiiR  Kvill 

i!):'.(i 

Xnniial  Flow 
1916 

I'OI. 

ulatkiii 

Sewage  in 

r^ 

Velocity 

Di.s- 

Depth 

Veloc- 

Tri 

butaiy 

Secouil  ft. 

(Irade 

('ai)ac 

ft. 

cliarge 

of 

ity  ft. 

1910 

1936 

1916               1936 

Dia. 

Sec.  ft. 

per  Sec. 

Sec.  ft. 

Sewer 

per  Sec. 

54.000 

127,334 

13.93      32.84 

36" 

0.286 

32.0 

4.4 

5.57 

10.08" 

3.04 

60.000 

146,000 

15.47      37.65 

39" 

0.286 

37.5 

4.7 

6.19 

10.92" 

3.24 

60.000 

146,000 

15.47       37.65 
Future 

39" 
Thirty 

0.33 
Years 

41.1 

5.0 

6.19 

10.14" 

3.30 

54,000 

170,692 

13.93       44.01 

42" 

0.286 

47.5 

4.9 

5.57 

9.66" 

2.99 

60,000 

196,000 

15.47       50.55 

45" 

0.286 

57.0 

5.1 

6.19 

9.90" 

3.00 

60,000 

196,000 

15.47       50.55 
Future 

45" 
Forty 

0.33 
Years 

61.0 

5.5 

6.19 

9.45" 

3.19 

54,000 

216,667 

13.93      55.88 

45" 

0.286 

57.0 

5.1 

5.57 

9.45" 

2.96 

60,000 

250,000 

15.47      64.47 

48" 

0.286 

68.0 

5.4 

6.19 

9.60" 

3.02 

60,000 

250,000 

15.47      64.47 

48" 

0.33 

72.0 

5.7 

6.19 

9.60" 

3.19 

From  the  above  figures,  it  is  seen  that  a  circular  sewer 
designed  for  a  forty  year  future,  according  to  conditions  as- 
sumed, would  have  sufficient  velocity  during  times  of  normal 
flow,  during  the  first  few  years  of  its  life.  During  several 
hours  of  the  day  the  flow  would  drop  considerably  below  the 
normal,  and.  at  these  times,  the  velocities  would  probably  drop 
below  the  critical  point.  At  such  times,  however,  the  sewage 
flow  is  mostly  water,  containing  a  very  small  percentage  of 
suspended  solids.  Any  depositing  of  solids,  therefore,  would 
not  be  serious  and  would  be  flushed  away  within  a  few  hours, 
with  the  approach  to  normal  flow. 

Economic  considerations  generally  require  the  construc- 
tion of  a  main  or  outfall  sewer  to  meet  future  rather  than  pres- 
ent needs.  The  first  cost  of  a  large  sewer  is  much  less  in  pro- 
portion to  the  capacities  than  a  smaller  sewer,  but  the  con- 
struction of  a  sewer  adequate  to  meet  the  needs  of  a  popula- 
tion at  long  periods  in  the  future,  often  becomes  too  great  a 
burden  upon  the  present  population.  In  such  cases  a  smaller 
sewer  is  advisable.  From  the  preceding  figures  it  is  seen  that 
the  difference  in  first  cost  between  a  sewer  to  serve  for  twenty 
years  and  one  to  serve  for  forty  years  is  $25,564.  and  between 
thirty  and  forty  years,  $4,703. 

Considering  then  the  conditions  of  growth,  as  we  have 
estimated  them  and  a  sewer  constructed  for  a  twenty  3'ear 
future : — During  the  first  few  years  of  the  life  of  this  pipe  the 
annual  charges,  interest  and  sinking  fund  would  be  less  than 

31 


in  the  cost  of  a  forty  year  sewer,  but,  at  the  end  of  twenty 
years,  such  a  sewer  would  be  inadequate  and  would  either  have 
to  be  abandoned  and  a  larger  sewer  l^uilt,  or  a  duplication 
made. 

If  a  duplication,  the  capacity  of  the  two  sewers  would  be 
doubled  and  twice  the  population,  or  292,000  people  could  be 
served.  AMth  the  larger  pipe  the  capacity  is  72  second  feet  and 
at  one  hundred  and  twenty-five  gallons  per  capita,  279,190 
people  could  be  served.  The  first  cost  of  the  two  smaller  pipes 
to  serve  292,000  would  be  $122,980,  while  the  first  cost  of  the 
larger  pipe,  which  would  have  practically  the  same  life,  would 
be  $87,054.  There  would,  however,  be  a  saving  made  in  favor 
of  the  smaller  pipe  in  the  interest  earnings  during  the  first 
twenty  years. 

The  difTerence  in  first  cost  between  the  smaller  sewer  and 
the  larger  sewer  is  $25,564,  which  would  earn  in  twenty  years 
at  4.5%  compound  interest,  $36,086.  The  first  cost  then,  in  the 
case  of  the  two  small  sewers  would  be  $86,894  against  $87,054 
for  the  larger  sewer.  These  figures,  however,  do  not  take  into 
account  the  addition  in  unit  cost  due  to  the  tearing  up  of  pave- 
ments and  their  replacement,  which  would  no  doubt  have  to 
be  met  twenty  years  hence  in  the  construction  of  a  duplicate 
sewer. 

After  a  careful  consideration  of  the  above  figures,  we 
believe  it  advisable  to  construct  the  larger  sewer,  and  would 
recommend  this  course  to  your  Honorable  Bodies. 

TREATMENT  PLANT:— In  the  selection  of  the  most 
suitable  method  of  purification  adaptable  to  the  needs  of  the 
three  cities,  the  following  two  factors  were  considered : — 

( 1 )  The  degree  of  purification  necessary. 

(2)  A  plant  to  give  the  desired  purification  at  the  least 

cost. 
Degree  of  Purification  Necessary. — We  believe  that  the 
land  purchased  for  farming  and  disposal  of  the  sewage  effluent 
thereon  is  sufficiently  remote,  at  the  present  time,  from  resi- 
dential property  that  clarified  sewage  effluent  could  be  used 
for  irrigation,  without  creating  any  nuisance  whatever.  And, 
if  the  cities  owned  sufficient  land  to  use  such  effluent  at  all 
times  for  irrigation   purposes,   no   further  purification    would 

32 


be  necessary.  There  will  be  times,  however,  when  the  cities 
will  be  unable  to  use  the  effluent  to  advantage,  or  to  sell  it  to 
near-by  ranchers,  and  at  such  times  it  will  be  necessary  to  turn 
the  effluent  into  the  natural  drainage  channels  and  thence  into 
the  river.  If  this  is  to  be  done  a  high  state  of  stability  would 
be  required,  that  no  nuisance  from  odors  or  the  pollution  of 
the  streams  result. 

It  is  necessary  that  a  modern  purification  plant  be  in  con- 
tinual operation,  if  results  are  to  be  obtained,  for  it  requires 
some  time  (a  few  days  to  a  few  weeks)  for  a  filter  to  ripen  and 
the  growth  of  the  proper  bacterial  jelly  to  form.  Therefore,  if 
at  times  sewage  must  be  turned  into  the  streams  and  stability 
is  necessary,  a  purification  plant  must  be  provided  and  be  kept 
in  continual  operation. 

A  Plant  to  Give  the  Desired  Purification  at  the  Least  Cost. 

We  would  recommend  to  your  Honorable  Bodies  that  the 
following  treatment  plant  be  constructed : — 

Imhofif  clarification  tanks,  followed  by  sprinkling  filter 
beds,  secondary  Imhoff  sedimentation  tank  and  sludge  drying 
beds. 

We  recommend  this  type  of  plant  for  the  reason  that  to- 
day it  is  the  most  efficient,  proven  plant,  and  will,  under  proper 
management  and  design,  give  non-putrescible  and  therefore 
stable  effluent  at  least  cost.  A  description  of  a  plant  of  this 
kind  follows,  together  with  a  set  of  complete  plans. 

Before  entering  the  treatment  plant,  the  sewage  will  pass 
through  a  coarse  bar  screen  of  3^"x2"  iron  bars,  spaced  2" 
center  to  center  and  inclined  45°  to  the  horizontal.  This  screen 
will  catch  any  large  matter  that  may  find  its  way  into  the 
sewer  and  cause  trouble  in  the  throat  of  the  X'enturi  meter. 
The  screen  can  be  cleaned  once  or  twice  a  day  by  hand.  From 
the  screen,  the  sewage  will  pass  through  a  30"  x  8"  Venturi 
meter,  which  will  be  connected  with  an  indicator  and  record- 
ing disk  in  the  office  of  the  laboratory  adjoining.  This  will 
register  automatically  the  flow  of  sewage  at  all  times. 

CLARIFICATION— IMHOFF  DESIGN  :— These  tanks 
are  six  in  number,  each  containing  three  sludge  comjjartments. 
Each  tank  is  designed  to  serve  10,000  inhabitants  with  a  deten- 

33 


tion  period  of  three  hours.  Combined,  the  tanks  will  serve 
for  a  period  of  five  years.  Inasmuch  as  it  is  poor  policy  to 
construct  new  tanks  every  year,  this  five  year  period  was 
adopted  by  this  Board.  There  is  sulTficient  room  to  extend 
these  tanks,  when  the  future  growth  exceeds  the  present  de- 
signed capacity.  The  detention  period  calculated  for  the  pres- 
ent time  can  easily  be  shortened,  if  found  necessary,  by  regu- 
lating the  gates  in  the  influent  channel.  The  following  figures 
show  how  this  detention  period  was  calculated : 

Sectional  area  of  sedimentation  chamber  =  182.52  square 
feet.  Length— 62  ft.  62  ft.  x  182.52  sq.  ft.  =  1 1,316.24  cu.  ft.  = 
capacity  of  each  tank.  Normal  flow  3,000,000  in  eighteen  hours 

3,000,000      „.Qi^,  ,,  ,  r        •     ,     1 

:r^ — Z  ,rs  =22,281.64  cu.  It.  per  hour  for  six  tanks  or 

18x/.48  ^ 

99  981 64  -  -  -      -  ^         .         . 

'"     ' —    cu.  ft.  =  3,/ 13.61  cu.  ft.  for  each  tank.     Capacitv  ot 
6 

tank  =    J~.  -'"-^3.047    hours    detention    period    or    flowing- 
3,713.61 

through  time.  \Mth  a  maximum  flow  of  7,500,000  gallons  for 
eighteen  hours,  using  the  above  formula  gives  1.22  hours  de- 
tention period.  The  velocity  in  the  tanks  under  these  condi- 
tions is  about  twenty  feet  per  hour  for  normal  flow  and  forty 
feet  per  hour  for  maximum  flow. 

The  sludge  compartments  for  each  tank  are  designed  with 
a  storage  capacity  of  five  months,  based  upon  0.00525  cu.  ft. 
of  sludge  per  capita  per  day.  The  scum  chambers  will  have 
an  area  equal  to  20%  of  the  total  area  of  the  tank. 

Inlet  channels  are  to  be  constructed  which  will  permit 
reversing  the  flow  of  sewage  through  the  tanks.  If  the  sewage 
were  to  enter  the  tank  at  one  end  only,  there  would  be  a 
greater  deposit  of  solids  in  the  sludge  chamber  at  this  point 
and  would  decrease  as  it  approached  the  opposite  end  of  the 
tank.  Consequently,  by  reversing  the  flow  every  two  or  three 
weeks,  a  more  even  distribution  of  the  settling  solids  will  be 
obtained. 

These  inlet  channels  will  have  a  semi-circular  bottom  and 
will  be  constructed  without  covers.  This  will  facilitate  the 
work  in  cleaning  out  any  sediment  which  may  collect  in  them. 

The  sludge  will  be  drawn  ofT  by  means  of  8"  cast  iron 
pipes  laid  beneath  the  tanks,  and  connecting  the  sludge  com- 

34 


partments  of  each  tank  to  a  man-hole.  This  method  will  allow 
the  cleaning  out  of  any  tank,  without  resorting  to  pumps.  A 
perforated  water  pipe  will  be  placed  within  the  tanks.  If  any 
difificulty  is  found  in  removing  the  sludge,  in  that  a  cone  might 
be  formed  through  wdiich  water  instead  of  sludge  might  pass, 
by  forcing  water  through  the  perforated  pipes,  the  sludge 
Avould  be  agitated  and  the  trouble  remedied. 

As  the  solids  accumulate  in  the  sludge  chamber,  they  un- 
dergo a  biolytic  disintegration  and  physical  consolidation,  de- 
creasing the  volume  and  water  content. 

The  main  walls  of  the  tanks  are  designed  as  reinforced 
concrete  walls,  inner  partition  walls  of  cement  plaster  on  Hy- 
rib  metal  lath,  supported  by  a  frame-work  of  steel  angles.  All 
metal  to  be  covered  with  concrete. 


PURIFICATION  PLANT 

Dosing  Tanks.  From  the  Imhoff  tanks,  the  clarified  ef- 
fluent will  flow  in  an  open  channel  to  the  dosing  tanks,  two  in 
number,  of  18,000  gallons  capacity  each.  Stop  gates  and  ad- 
justable weirs  are  provided,  so  that  the  flow  to  either  tank  can 
be  regulated.  The  tanks  are  reinforced  concrete  (see  plan 
No.  3)  and  designed  as  taper  tanks  ;  this  diminishing  of  volume 
with  the  diminishing  of  head,  gives  a  better  distribution  of 
the  sewage  over  the  filter  rock.  Each  tank  is  provided  with 
a  30"  automatic  Miller  siphon,  with  provision  for  raising  or 
lowering  both  the  high  and  low  heads.  The  normal  head  will 
be  eight  and  one-half  feet  above  the  nozzle  dome,  and  normal 
minimum,  two  and  one-half  feet. 

Sprinkling  Filters.  From  the  dosing  tanks,  the  effluent 
passes  through  a  distributing  system,  as  shown,  to  two  units 
of  sprinkling  filters,  one  and  one-half  acres  each,  or  a  total  of 
three  acres.  The  distributing  system  is  assigned  to  cut  the 
loss  of  head  to  a  minimum,  and  in  our  plans  is  shown  as  cast 
iron.  It  is  possible  to  use  concrete  or  vitrified  pipe  encased 
in  concrete  for  the  construction,  and  a  considerable  saving 
would  be  made  if  this  type  were  used.  Such  construction,  how- 
ever, has  not  proven  satisfactory.  Leaks  occur  frequently 
which  are  difBcult  and  costly  to  repair,  owing  to  the  fact  that 
some  six  or  seven  feet  of  filter  rock  have  to  be  moved.     We 

35 


would  therefore  recommend  the  additional  first  cost  of  cast 
iron  construction. 

The  main  distributors  are  of  36"  and  30"  cast  iron  ;  the  lat- 
eral distributors,  which  feed  the  sewage  to  the  sprinkling  noz- 
zles, are  6"  and  12"  cast  iron  pipe  laid  on  the  floor  of  the  filter 
with  cast  iron  tees  to  receive  the  risers.  The  risers  are  of  3" 
cast  iron  pipe  with  bells  at  the  top  to  receive  the  nozzles.  Noz- 
zles are  spaced  fifteen  feet  center  to  center  in  triangle  arrange- 
ment, and  are  designed  to  throw  circular  sprays.  The  varia- 
tion of  the  head  at  the  dosing  tanks  (already  mentioned)  will 
vary  the  spray  proportionately. 

The  filters  will  have  an  average  depth  of  6.75  feet  from 
the  surface  of  the  rock  to  the  floor,  and  an  average  depth  of 
6.25  feet  above  the  under-drainage  system.  The  filter  ma- 
terial will  be  of  1^"  to  2"  broken  stone,  character  not  yet  de- 
termined. The  floors  of  the  filters  are  of  3"  reinforced  con- 
crete, with  a  ridge  at  the  center  of  each  bed,  the  floor  dropping 
3^-foot  from  the  center  to  the  collectors  at  the  sides.  The  col- 
lectors are  in  the  form  of  concrete  channels  with  circular  in- 
verts, and  are  one  foot  deep  at  the  upper  ends  and  two  feet 
deep  at  the  lower,  thus  giving  a  fall  of  one  foot  in  three  hun- 
dred and  ten  feet,  or  a  gradient  of  0.32%.  The  crushed  stone 
will  rest  on  a  false  floor  system  of  6"  vitrified  half  tile  drain 
laid  on  the  cement  floor  before  it  is  set.  This  should  give  am- 
ple drainage  capacity  and  insure  rapid  removal  of  the  effluent. 

The  channels  are  covered  with  reinforced  concrete  slabs, 
spaced  with  open  joints.  At  the  upper  ends  of  the  channels, 
8"  cast  iron  pipe  extends  up  through  the  filter  rock,  thus  giving 
a  means  of  flushing  out  the  channels  if  found  necessary. 

The  sprinkling  filters  are  favorably  located  from  a  stand- 
point of  construction  cost,  the  north  and  south  lines  being  en- 
tirely within  excavation,  while  the  center  of  the  beds  is  ap- 
proximately upon   the   present  ground   surface. 

The  east  and  west  lines  of  the  beds  are  in  fill,  but  there 
will  be  sufficient  earth  excavation  to  more  than  make  this  fill 
and  embankment.  The  outside  partition  walls  are  shown  as 
constructed  of  2"  cement  plaster  on  rib-metal  lath.  The  cost 
of  this  construction  will  be  much  less  than  either  a  gravity 
wall  or  a  reinforced  type  of  wall,  and  will  answer  the  purpose 
as  well.     The  wall  will  not  be  subjected  to  lateral  pressure  in 

Z6 


any  way,  as  these  forces  will  be  counterbalanced  by  earth  em- 
bankment on  the  one  side  against  rock  filUng^  on  the  other. 

Throug^h  the  center  of  the  beds  and  separating  one  from 
the  other,  we  have  allowed  for  a  gallery  to  contain  the  main 
distributing  pipes  and  gate  vales.  The  rock  of  the  filter  is  re- 
tained by  reinforced  cantilever  walls  the  full  length  of  the  beds. 

Means  have  been  provided,  if  it  is  necessary  at  any  time  to 
cut  out  the  beds,  by  passing  the  untreated  sewage  directly  to 
the  main  collectors,  by  shutting  the  lateral  gate  valves  and 
opening  24"  sluice  gates. 

The  effluent,  after  having  passed  through  the  filter,  will 
be  collected  by  a  main  collector  of  24"  and  36"  concrete  pipe 
laid  on  a  grade  of  0.3%  and  thence  to  the  secondary  settling- 
tank,  yisiu  holes  are  provided  for  a  ready  inspection  of  the 
collection  system  and  the  cleaning  of  same  if  found  necessary. 

The  filters  are  designed  for  a  population  of  60,000.  each 
acre  serving  a  population  of  20,000.  Under  normal  flow,  this 
will  give  a  rate  of  1,000,000  gallons  per  acre  daily.  \\'ith  do- 
mestic sewage,  rates  as  high  as  2,000,000  gallons  per  acre  daily 
can  be  handled  by  such  filters,  giving  good,  non-putrescible 
effluents.  On  a  basis  of  fifty  gallons  per  capita  daily,  the 
average  at  the  present  time,  three  acres  of  sprinkling  filters, 
at  a  rate  of  2,000,000  gallons  per  acre  daily,  would  handle 
6,000.000  gallons  per  day,  or  a  population  of  120,000  could  be 
cared  for. 

These  filters,  therefore,  based  upon  our  prediction  of  fu- 
ture growth,  should  meet  the  requirements  for  a  period  of 
fourteen  years  before  additional  beds  would  be  required.  With 
the  present  agreement  between  Pasadena.  South  Pasadena  and 
Alhambra,  Pasadena  will  have  three  years  in  which  to  discon- 
tinue the  use  of  sewage  on  her  present  farm.  Alhambra,  with 
no  internal  sewerage  system  at  present,  would  probably  need 
some  two  or  three  years  before  all  of  her  sewage  would  reach 
the  plant.  In  consideration  of  these  facts,  we  would  advise 
that  bonds  be  voted  by  those  cities  for  which  the  voting  of 
bonds  will  be  necessary,  for  the  entire  three  acres  as  planned, 
but  at  present  only  one  unit  or  one  and  one-half  acres  would 
be  constructed.  Bonds  for  the  remaining  portion  could  be 
held  and  sold  at  such  times  as  the  additional  unit  would  be 
needed. 

27 


SECONDARY  CLARIFICATION  TANK:— In  plan- 
ning for  a  secondary  tank  treatment,  we  have  designed  one  of 
the  Imhofif  type,  in  order  to  overcome  the  objectionable  feat- 
ures of  the  plain  sedimentation  tank.  This  is  accomplished  by 
allowing  the  sludge  to  accumulate  for  a  period  of  one  hundred 
and  sixty  days,  thus  providing  ample  time  for  its  ripening  and 
complete  decomposition.  The  capacity  of  this  tank  will  be 
31,769.60  cubic  feet  or  237,636.61  gallons.  With  a  normal  flow 
of  3,000,000  gallons  in  eighteen  hours  this  gives  166,666  gallons 

Der  hour  7  -^  v^^  =  l--^3  hours  which  is  the  detention  period. 
^  ■    loo  ,666 

For  a  maximum  flow  of  7,500,000  gallons,  or  two  and  one-half 
times  the  normal  flow  gives  0.57  hours  detention.  The  sludge 
compartment  contains  12,506  cubic  feet,  and,  assuming  that 
the  amount  of  sludge  formed  in  the  secondary  tank  is  one- 
fourth  the  amount  formed  in  the  preliminary  tanks,  gives  a 
detention  period  of  one  hundred  and  sixty  days.  The  with- 
drawal of  the  sludge  and  the  arrangement  of  the  perforated 
water  pipes  is  the  same  as  in  the  preliminary  tanks. 

Loss  of  Head  in  Plant.  ,,,^^^,.„„  „,!-«, 

in  feet        in  feet 

Elevation  normal  flow  line   Imhoff  Primarj'  tanks 341.00 

Elev-ation  normal   high-water  level  dosing  tanks 337.00  4 

Elevation  normal  nozzle   dome    sprinkling   filter 328.41  8.59' 

Elevation  average    flow,    sprinkling    iilters 321.25  7.16' 

Elevation  flow    line    secondary    settling    tanks 317.64  3.61' 

Total    Loss    Head 23.36' 

SLUDGE  DRYING  BEDS  :— A  drying  area  of  350  square 
feet  for  every  1000  persons  tributary  to  the  disposal  works  is 
the  general  practice,  the  frequency  of  removal  being  one  of 
the  controlling  factors  in  determining  the  area  required.  In 
California,  with  our  warm,  dry  climate  and  the  infrequency  of 
rain,  drying  of  sludge  from  an  Imhofif  tank  has  proven  to  be  a 
simple  matter.  Rain  has  practically  no  retarding  efifect  on 
drying,  except  that  there  would  be  the  additional  time  required 
to  drain  oflf  the  rain  water.  The  dried  result  has  the  same 
characteristics  as  that  which  has  been  dried  in  fine  weather. 

In  the  plans  submitted  we  have  provided  for  a  drying 
area  of  21,000  square  feet.  This  drying  bed  will  consist  of 
sand  and  gravel  one  foot  deep,  under-drained  with  three-inch 

38 


tile  leading  to  a  six-inch  tile  collector.  There  will  be  twenty 
separate  drying  beds,  each  fifty  feet  in  length  by  twenty-one 
feet  in  width,  separated  by  two-inch  redwood  partitions. 
Through  the  center  of  the  bed  there  will  be  a  twelve-inch 
concrete  partition  wall.  Running  into  each  bed  will  be  a 
twenty-four-inch  gauge  track,  with  twelve  pound  steel  rails  on 
steel  ties.  Cars  can  then  be  run  directly  onto  the  beds  and 
the  sludge  loaded  and  removed  for  future  disposal.  By  di- 
viding the  drying  area  into  smaller  units  by  means  of  the 
redwood  partitions,  the  small  beds  can  be  filled  and  emptied 
independently,  and  thus  all  the  stages  of  the  draining  can  be 
in  operation  at  once. 

The  sludge  is  drained  from  the  bottom  of  the  hopper- 
shaped  compartments  in  the  Imhoff  tanks  by  opening  valves 
and  permitting  the  sludge  to  flow  through  the  discharge  pipe. 
The  pressure  of  the  liquid  above  the  sludge  compartment 
greatly  facilitates  the  withdrawal.  Care  must  be  taken  that 
the  sludge  is  not  withdrawn  too  rapidly,  as  fresh  sludge  would 
then  be  drawn  ofif  with  the  fully  decomposed  sludge. 

Sufficient  fall  has  been  provided  in  the  design  and  location 
of  the  drainage  beds  in  order  that  the  sludge  will  readily  flow^ 
from  the  tanks  to  the  beds.  There  it  will  be  spread  in  layers 
from  eight  to  twelve  inches  in  depth,  regulated  according  to 
the  requirements.  The  withdrawal,  draining  and  drying  and 
final  disposition  of  the  sludge  from  this  type  of  tank  is  so  re- 
markably simple  and  satisfactory  that  it  is  one  of  the  chief 
characteristics  of  this  method  of  treatment. 

ESTIMATES  OF  COST 

Cost  includes  contractor's  profit  and  Workmen's  Compen- 
sation insurance,  but  does  not  include  engineering,  inspection, 
legal  and  general  expenses. 

Outfall  Sewer 

7,1  (X)  lin.  ft.  45"  brick  circular  sewer   $28,400.00 

11,300  lin.  ft.  48"  brick  circular  sewer   49,917.00 

Total  18,400  lin.  ft.     brick  circular  sewer $78,317.00 

40  Man-holes,  average  depth  12' 2,400.00 

Venturi  Meter  30"  x  8"  complete 1,500.00 

Bar  screen  and  chamber 100.00 

Total     $82,317.00 

39 


Imhoff  Tanks 

Excavation,  8,800  cu.  yards  $  6,600.00 

Concrete,  1,935  cu.  yards  22,475.00 

Inner  partition  walls,  Hy-rib  cement  plaster 3,550.00 

Sludge  pipe  and  fittings,  valves,  gates,  etc. 3,100.00 

6  brick  man-holes   300.00 

Water   system   900.00 

Total  $36,925.00 

Springling  Filter 

Excavation  18,180  cu.  yards $  6,364.40 

Exterior  walls— 10,241  sq.  ft.  1,740.97 

Reinforced  concrete  walls  3,210.00 

Floor    system    31,620.00 

Channels    476.00 

Man  holes  300.00 

Effluent   collectors   1,081.20 

Distribution    system    22,848.00 

48,  12"  hub  end  gate  vales 1,680.00 

2—24"    shear    gates    276.00 

Sprinkling  nozzles,  648  1,101.60 

Crushed  rock,  31,868  yds.  71,703.00 

Total    $142,401.17 

Final  Settling  Basins — Imhoff  Type 

Excavation,  2,571   cu.  yds.  - $  1,928.00 

Concrete,  584  yds.   6,583.00 

Influent    pipe,    36"    concrete 448.20 

Inner   partition  walls,   Hy-rib  cement   plaster 1,520.05 

Effluent    pipe    36"   -concrete 422.00 

7  man-holes   - 350.00 

Cast  iron  pipe  and  iittings,  gate  valves 385.00 

10"  vitrified   pipe   90.00 

Water   system    250.00 

Total     $1 1 ,976.25 

Sludge  Beds 

Excavation,  1,000  cu.  yds.  $  300.00 

Concrete  walls   (plain)   825.00 

Wooden  partition  walls  165.00 

Under  drainage  system  500.00 

Track,  switches  and  two  cars 2,181.00 

Sludge  pipe  and  valves  458.00 

Sand  133  yards  200.00 

Rock  652  yards  1,304.00 

Total  $  5,933.00 

Cost — Miscellaneous  Items 

Sludge  pipe,  tanks  to  beds $      640.00 

Water  pipe  and  fittings  about  plant 635.00 

Water  main  south  line  tract  No.  786  to  plant 2,310.00 

Open   channel   from   Imhoff  tanks   to  dosing  tank 1,050.00 

Total     $  4,635.00 

40 


Dosing  Tank 

2—30"    Miller    siphons    complete $  2,500.00 

Excavation  710  yards  355.00 

Concrete,  109  yards  886.00 

$  3,741.00 

Laboratory    building   1,000.00 

Equipment  500.00 

Total  $  5,241 .00 

Total     cost    of    entire    plant    and    outfall     sewer, 

exclusive  of  land  $289,428.42 

Plus  10%   engineering,  inspection,  miscellaneous.—       28,942.84 

Total  318,371.26 

Proportioning  the  costs  and  maintenance  of  the  outfall  sewer 
and  purification  works,  and  the  maintenance  and  revenue  of 
the  farm. 

The  outfall  sewer  and  the  purification  works  are  desis^ned 
to  provide  for  the  disposal  of  the  sewage  from  a  given  pop- 
ulation, consequently  the  proportioning  of  the  costs  and  main- 
tenance should  be  on  a  population  basis.  A  careful  study  of 
the  population  chart  accompanying  this  report  reveals  the  fol- 
lowing facts,  viz :  That  the  combined  population  of  the  three 
cities,  their  respective  population  and  percentage  of  the  com- 
bined population  are  as  follows : 


Year 

Amt. 

Pasadena 

'I'l 

S.  I'a.sadiMui 

Alhambra 

% 

1916 

60,000 

42.000 

70 

8,000 

13.3 

10.000 

16.6 

1921 

80,000 

54,000 

67.5 

12,000 

15 

14,000 

17.5 

1931 

123,000 

82,000 

66.6 

18,000 

14.7 

23,000 

18.7 

1941 

170,000 

1 1 1 ,000 

65.3 

26,000 

15.3 

33,000 

19.4 

1951 

220,000 

142.000 

64.5 

34,000 

15.5 

44.000 

20 

1956 

250,000 

160,000 

64 

40.000 

16 

50.000 

20 

and  the  average  of  the  percentage  of  each  city  is  ;  Pasadena 
66.3%  ;  South  Pasadena  15%.  and  Alhambra  18.7%. 

If  we  consider  the  proposition  that  each  of  the  three  cities 
were  to  build  a  separate  outfall  sewer  to  the  new  farm,  we 
find  that  it  would  cost  Pasadena  $77,924 ;  South  Pasadena  $38.- 
244,  and  Alhambra  $38,640,  the  total  of  which  is  nearly  twice 
the  cost  of  a  joint  outfall  sewer. 

Pasadena  now  owns  two-thirds  of  the  new  farm.  South 
Pasadena  one-sixth  and  Alhambra  one-sixth,  and  the  estimated 
proportions  to  each  city,  according  to  popidation,  are  approx- 
imately two-thirds,  one-sixth,  and  one-sixth. 

41 


The  estimated  cost  of  a  joint  outfall  sewer  on  the  basis 
of  two-thirds  to  Pasadena,  one-sixth  each  to  South  Pasadena 
and  Alhambra,  is  as  follows : — 

Pasadena,   two-thirds   of  $87,054 $58,036.00 

South  Pasadena,  one-sixth  of         87,054 14,509.00 

Alhambra,  one-sixth  of  87,054 14,509.00 

Total  $87,054.00 

From  these  figures  the  saving  in  favor  of  a  joint  outfall, 
to  each  city,  would  be ; 

Pasadena    $19,888.00 

South  Pasadena 23,735.00 

Alhambra     24,131.00 

\\'e  would  therefore  recommend  that  the  outfall  sewer  be 
proportioned  on  the  basis  of  Pasadena,  two-thirds.  South  Pasa- 
dena, one-sixth  and  Alhambra,  one-sixth. 

\\'e  realize  the  fact  that  any  attempt  to  make  an  adjust- 
ment at  stated  intervals,  as  when  the  United  States  census 
would  be  available,  would  be  a  very  difficult  proposition.  As 
the  United  States  census  is  only  taken  every  ten  years,  the 
three  cities  would  have  to  agree  on  allowing  any  radical  change 
which  might  occur  during  a  ten  year  period,  to  be  ignored,  or 
else,  numerous  and  costly  meters  would  have  to  be  installed 
and  maintained,  the  cost  of  which,  we  believe,  would  more 
than  offset  the  saving  between  meters  and  the  adoption  of 
the  percentage  basis.  Even  though  Pasadena  would  have  80% 
of  the  combined  population  at  the  end  of  forty  years,  and 
South  Pasadena  and  Alhambra  10%  each,  the  cost  of  separate 
outfalls  to  these  cities  would  still  amount  to  more  than  their 
portion  of  a  joint  outfall.  Considering  all  of  this,  w^e  believe 
our  recommendation  to  be  absolutely  fair  to  each  of  the  three 
cities. 

Any  maintenance  on  the  outfall  sewer  would  be  paid  on 
the  above  basis. 

PURIFICATION  WORKS :— The  capacity  of  the  purifi- 
cation works  depends  solely  upon  the  quantity  of  sewage  con- 
tributed by  the  three  cities,  and,  in  turn,  this  amount  depends 
upon  a  number  of  factors,  which,  at  the  present  time,  are  im- 
possible of  determination,  such  as ;  first,  the  character  of  and 
growth  of  the  cities  in  question,  whether  along  residential  or 

42 


industrial  lines ;  second,  the  increase  in  population  with  an 
increase  or  decrease  in  water  consumption.  With  this  in 
mind,  the  Board  of  Eng'ineers  do  not  believe  it  advisable  to 
make  any  fixed  rule  for  proportioning-  the  cost  of  future  exten- 
sions to  the  plant.  We  would  recommend  that  the  first  cost  of 
construction  be  met  by  the  three  cities  in  the  proportion  as 
used  in  determining  the  proportion  of  cost  in  the  outfall  sewer, 
such  proportionings  based  upon  present  percentages  of  popu- 
lation. If.  at  any  time  in  the  future,  it  is  found  that  extensions 
are  necessary,  a  survey  can  then  be  made  to  determine  the  pro- 
portionate costs. 

The  estimated  cost  of  outfall  sewer  and  the  purification 
plant,  exclusive  of  land,  is  $318,371.26  and  proportioned  to  the 
three  cities  on  the  basis  of  two-thirds  to  Pasadena,  one-sixth 
each  to  South  Pasadena  and  Alhaml)ra,  would  be  as  follows : — 

Pasadena    $212,247.50 

South  Pasadena  52,961.88 

Alhambra     52,961.88 

Total  $318,271.26 

In  addition  to  the  first  cost  to  the  cities  of  South  Pasadena 
and  Alhambra.  there  is  a  royalty  for  the  use  of  the  Patented 
Imhofif  tank.  Such  charge  to  Pasadena  has  already  been  paid 
to  Dr.  ImhofT,  based  on  a  population  of  60,000.  The  amount 
of  royalty  to  each  of  the  cities  of  South  Pasadena  and  Alham- 
bra will  be  $468.00  for  South  Pasadena  and  $533.00  for  Alham- 
bra, which  will  make  the  total  cost  to  the  three  cities  as  fol- 
fows : — 

Pasadena   $212,247.50 

South  Pasadena  53,429.88 

Alhambra    53,494.88 

OPERATION  AND  MAINTENANCE:— Costs  of  oper- 
ation and  maintenance  should  be  proportioned  to  the  three 
cities  according  to  their  share  as  represented  by  their  owner- 
ship in  the  plant.  Pasadena,  with  a  two-thirds  interest,  to  pay 
two-thirds  of  the  cost  and  South  Pasadena  and  Alhambra, 
each  with  a  one, sixth  interest,  should  pay  in  proportion. 

REVENUE: — Any  revenue  derived  from  the  plant  from 
selling  of  water  for  irrigation  or  other  uses,  or  the  disposal  of 
•sludge  shall  be  apportioned  as  in  the  case  of  cost  of  operation 
and  maintenance. 

43 


MAINTENANCE  OF  PURIFICATION  WORKS:— It 

is  absolutely  essential  that  efficient  supervision  be  constantly 
maintained  at  the  disposal  works.  The  three  cities  have  pledged 
themselves  to  the  public  to  maintain  a  highly  efficient  purifica- 
tion works,  and  without  efficient  supervision  this  would  be  im- 
possible. It  will  be  necessary,  at  all  times,  to  determine 
whether  or  not  sufficient  or  insufficient  quantities  of  sewage 
are  passing  through  the  Imhoff  tank  and  whether  the  sprink- 
ling filter  beds  are  working  successfully.  The  recording 
gauges,  the  dosing  apparatus  and  sprinkling  nozzles,  and  the 
secondary  tanks,  must  all  be  intelligently  inspected  and  kept 
in  perfect  order.  In  fact,  there  are  numerous  details  which 
will  have  to  receive  daily  attention.  There  is  only  one  solution 
for  this  and  that  is  the  employment  of  a  chemist  and  bacteriol- 
ogist, one  who  is  absolutely  familiar  with  a  purification  works 
such  as  we  have  designed.  The  entire  disposal  works  with 
the  nessary  help  and  attendants  will  be  in  his  charge,  and  the 
responsibility  for  the  successful  operation  of  the  plant  Avill  be 
entirely  in  his  hands,  ^^'^e  would  therefore  recommend  that 
such  a  man  be  employed  at  a  salary  of  not  less  than  $150  per 
month. 

A\'e  estimate  the  cost  of  operation  as  follows: — 

Chemist  and  bacteriologist  $1,800 

Three  attendants   (eight  hour  shifts) 2.700 

One  additional  day  man..... 900 

Estimated  total  cost  per  year $5,400 

FARM : — Pasadena  has  a  two-thirds  undivided  interest  in 
the  farm.  South  Pasadena  one-sixth  and  Alhambra  one-sixth. 
We  do  not  advise  any  adjustment  in  this  matter.  Any  subse- 
quent purchases  that  might  be  made  can  readily  be  propor- 
tioned between  the  three  cities  by  the  same  method  used  in  the 
])urchase  of  the  new  farm.  The  maintenance  of  the  farm  and 
all  revenues  should  be  jiroportioned  according  to  the  interest 
each  city  has  in  the  farm. 

CONCLUSION: — In  conclusion  we  wish  to  express  our 
appreciation  for  the  sup])ort  you  have  given  us  in  making  this 
report. 

44 


W  Iiilc  out  work  has  covered  a  period  of  over  one  year,  we 
feci  that  tliis  coukl  not  be  avoided  owing-  to  the  duties  which 
our  respective  offices  demanded  of  us.  (lur  report  would  not 
be  as  complete  as  it  is,  if  we  had  not  been  allowed  a  free  hand 
in  slathering  data,  making-  field  surveys,  maps,  etc.  While  at 
times,  the  work  has  been  arduous,  it  has  been  a  pleasure  to 
serve  your  Honorable  Bodies,  and  the  people  of  the  three  cities 
in  what  we  l)elieve  to  be  one  of  the  most  important  problems 
now  confronting"  the  people  of  this  country. 

We  wish  to  express  our  thanks  and  a])preciation  to  City 
and  State  officials  and  other  authorities  on  sewage  disposal, 
who  have  lieen  so  courteous  in  furnishing-  us  with  information 
and  data,  much  of  which  could  have  been  obtained  from  no 
other  source. 

Respecfully  submitted, 

R.  V.  ORBISON, 
CHARLES  E.  HEWES, 
JOHN  AfacAHLLAN. 


45 


SEWER  CONTRACT  BETWEEN  PASADENA,  SOUTH 
PASADENA  AND  ALHAMBRA. 

MEMORANDUM  OF  AGREEMENT  made  and  entered 
into  this  4th  day  of  December,  1914,  by  and  between  the  CITY 
OF  PASADENA  party  of  the  first  part,  hereinafter  called 
"Pasadena,"  the  CITY  OF  SOUTH  PASADENA,  party  of 
the  second  part,  hereinafter  called  "South  Pasadena,"  and  the 
CITY  OF  ALHAMBRA.  party  of  the  third  part,  hereinafter 
called  "Alhambra." 

\MTNESSETH  that 

\\'HEREAS  the  parties  hereto  are  municipal  corporations 
of  Los  Angeles  County.  State  of  California,  and  adjoin  each 
other ;  and 

\\'HEREAS,  Pasadena  has  a  practically  complete  interior 
sewer  system  by  which  its  sewage  is  discharged  through  the 
several  outfall  sewers  to  the  tract  of  land  which  it  owns  and 
which  is  known  as  the  "Pasadena  City  Farm."  situated  to  the 
south  and  east  of  the  City  of  Alhambra.  and  disposed  of  on  the 
aforesaid  City  Farm  by  means  of  sejitic  tanks,  and  one  (1)  of 
its  outfall  mains,  designated  as  the  Garfield  Avenue  main, 
passes  through   South    Pasadena  and   Alham1:)ra;   and 

A\'II  I'^REAS.  by  reason  of  the  to])ograpliical  conditions  in 
Pasadena  it  is  ncccssar}-  for  said  City  to  puni])  a  part  of  its 
sewage  which  is  collected  over  territory  lying  along  the  bank 
of  the  Arroyo  Seco  in  order  to  discharge  said  sewage  to  any 
of  its  outfalls ;  and 

\\TIFREAS.  South  Pasadena  has  recently  incurred  a 
bonded  indebtedness  in  the  sum  of  Two  Hundred  Thousand 
Dollars  ($200,000.00)  for  the  acciuisition  and  construction  of 
an  interior  sewer  system  and  the  necessary  means  of  disposal 
of  the  sewage  collected  in  such  interior  system,  and  has  act- 
ually constructed  a  considerable  portion  of  such  interior  sys- 
tem, and  desires,  as  speedily  as  jjossibie.  to  construct  or  ac- 
quire the  use  of  an  outfall  sewer  including  some  method  of 
disposing  of  the  sewage  without  a  delay  ;  and 

W'l  I  i'".  K  EAS.  tlie  Garfield  A\enue  main  of  the  Pasadena 
sewer  is  so  constructed  and  of  sufficient  capacity  that  it  can 
carry  ofif  the  sewage  of  South    Pasadena  and   Alhambra,  as 

46 


hereinafter  provided,  and  the  cHsposal  works  of  Pasadena  are 
available  for  use  in  the  handling  of  such  additional  sewage ; 
and 

WHEREAS,  good  engineering  dictates  that  South  Pasa- 
dena should  connect  its  interior  system  with  said  Garfield 
Avenue  main  and  through  its  interior  system  also  collect  cer- 
tain sewage  of  Pasadena,  which  is  now  being  pumped,  and 
which  will  be  a  distinct  advantage  to  Pasadena  ;  and 

WHEREAS,  the  parties  hereto  desire  to  enter  into  a  con- 
tract for  the  construction  and  maintenance  of  sewers  and  ac- 
quisition of  a  site  for  sewage  disposal  works  including  the 
construction  of  an  outfall  sewer  to  connect  said  Garfield  Ave- 
nue main  with  said  works,  for  the  joint  use  and  benefit  of  the 
parties  hereto,  said  contract  to  be  entered  into  pursuant  to  an 
Act  of  the  Legislature  of  the  State  of  California,  entitled  :  "An 
Act  Authorizing  Municipal  Corporations  to  Permit  Other  Mu- 
nicipal Corporations  to  Construct  and  Maintain  Sewers, 
A^^ater-Mains  and  other  Conduits  Therein,  also  to  Construct 
and  Maintain  Sewers.  Water-Mains  and  other  Conduits  for 
the  joint  Benefit,  and  at  their  Joint  Expense,  and  to  make  and 
Enter  into  Contracts  for  said  Purposes."  Approved  March  22, 
1909,  as  amended  by  amendment  approved  March  7th,  1911, 
and  pursuant  to  the  general  powers  of  said  Cities  as  expressed 
in  the  general  laws  or  their  charters. 

NOW  THEREFORE,  for  and  in  consideration  of  the 
mutual  covenants  and  agreements  herein  contained,  and  other 
good  and  valuable  considerations,  mutually  given,  the  receipt 
of  which  is  hereby  acknowdedged,  the  parties  hereto  do  hereby 
agree  as  follows : 

EIRST:  Alhambra  hereby  grants  to  South  Pasadena  the 
right  to  construct  and  maintain,  at  its  own  expense,  a  sewer 
main  in  and  along  Alhambra  Road  from  Huntington  Drive  to 
Fremont  Avenue  to  be  constructed  of  ten  (10)  inch  vitrified, 
salt  glazed  sewer  pipe,  or  standard,  glazed,  machine-made,  ce- 
ment pipe,  together  with  necessary  laterals  to  property  line  of 
abutting  property ;  and  also  in  and  along  Alhambra  Road  from 
Fremont  Avenue  to  Marengo  Avenue  in  South  Pasadena,  a 
fourteen  (14)  inch  main  of  the  kind  and  under  the  conditions 
recited  above ;  and  along  Alhambra  Road  from  said  Marengo 

47 


Avenue  to  a  point  approximately  three  hundred  and  seventy- 
five  (375)  feet  east  of  said  Marengo  Avenue,  a  twenty-one  (21) 
inch  pipe  of  the  kind  and  under  the  conditions  recited  above ; 
and  along  Alhambra  Road  from  -a  point  approximately  three 
hundred  and  seventy-five  {375)  feet  east  of  said  Alarengo  Ave- 
nue to  Garfield  Avenue ;  thence  south  on  Garfield  Avenue  to  a 
point  approximately  seventy  (70)  feet  south  of  the  intersection 
of  Grand  Avenue  and  Garfield  Avenue,  to  there  connect  with 
the  Pasadena  Garfield  Avenue  main,  a  twenty-seven  (27)  inch 
brick  or  reinforced  concrete  sewer  under  the  conditions  above 
recited. 

This  permission  is  granted  SUBJECT  to  the  following 
conditions : 

(a)  The  owners  of  property  in  Alhambra  abutting  on 
said  sewer  shall  have  the  right  to  connect  their  premises  there- 
with, without  the  payment  of  any  charge  or  fee  imposed  by 
South  Pasadena ; 

(b)  Alhambra  shall  have  the  right  to  construct  sewers 
and  connect  them,  without  cost  as  in  subdivision  (a)  next 
above,  with  said  sewer  main,  as  far  as  necessary  to  serve  the 
territory  naturally  tributary  to  said  main  : 

( c)  South  Pasadena,  in  constructing  said  main,  shall  be 
subject  to  the  general  police  ordinance  of  Alhambra  in  respect 
to  making  excavations  in  its  streets  and  the  refilling  of  same ; 

(d)  The  City  of  Alham1)ra  shall  have  the  right  to  deter- 
mine the  depth  and  location  of  said  main  ; 

(e)  Any  litigation  arising  out  of  the  construction  or  oper- 
ation of  said  main  by  South  Pasadena  shall  be  conducted  by 
said  City  of  South  Pasadena,  and  the  expense  thereof  shall 
be  borne  entirely  by  it. 

Pasadena  hereby  grants  to  Alhambra  the  right  to  use  the 
Garfield  Avenue  main  for  all  property  along  the  line  of  said 
main  for  a  distance  of  four  hundred  (400)  feet  on  either  side 
of  said  Avenue,  which  Alhambra  may  desire  to  connect,  or 
cause  or  permit  to  be  connected  with  said  Garfield  Avenue 
main,  without  any  charge  therefor. 

The  City  of  Alhambra  shall  have,  and  is  hereby  granted 
the  right  to  connect  its  interior  sewer  system  when  con- 
structed, or  any  portion  thereof  when  constructed,  with  the 

48 


outfall  sewer  to  be  constructed  in  accordance  with  this  agree- 
ment, and  to  use  said  outfall  sewer  and  the  disposal  works 
connected  therewith  for  treatment  and  care  of  sewage  in  ac- 
cordance with  the  terms  of  this  agreement. 

South  Pasadena  may  connect  its  sewer  main  constructed 
as  above  provided,  with  the  Pasadena  Garfield  Avenue  main 
at  the  place  there  specified,  for  which  permission  is  hereby 
granted  by  Pasadena  and  may  discharge  sewage  collected  by 
its  interior  sewer  system  and  the  sewage  of  Pasadena  re- 
ceived in  said  interior  s}'stem  as  described  in  the  recitals 
hereof,  and  the  Alhambra  sewage  discharged  into  its  main  as 
above  provided,  in  subdivisions  (a)  and  (h)  aforesaid,  into  said 
Garfield  Avenue  main.  Sewage  thus  discharged,  and  other- 
wise discharged  by  Alhambra,  as  in  paragraph  next  above 
provided,  will  be  treated  and  cared  for  by  the  City  of  Pasadena, 
together  with  its  sewage  in  a  sanitary  manner,  so  as  not  to 
constitute  a  menace  to  public  health,  until  the  ])resent  sewer 
farm  is  abandoned  as  hereinafter  provided. 

SECOND:  The  use  by  Pasadena  of  the  interior  sewer 
system  of  South  Pasadena,  the  right  to  use  which  is  hereby 
granted,  shall  be  deemed  to  compensate  Pasadena  for  allowing 
the  use  of  its  Garfield  Avenue  main  as  provided  in  the  first 
paragraph  hereof. 

THIRD  :  It  is  anticipated  that  during  certain  months  of 
the  year  Pasadena  will  be  put  to  additional  expense  in  caring 
for  sewage  discharged  on  its  farm  by  South  Pasadena  and  Al- 
hambra through  the  Garfield  Avenue  main,  by  reason  of  the 
additional  amount  of  sewage  discharged  from  said  main  as 
a  result  of  the  arrangement  provided  for  by  this  contract. 
South  Pasadena  will,  on  demand,  compensate  Pasadena  for 
any  such  additional  expense. 

FOURTH :  The  City  Engineers  of  AlhamlM-a,  South 
Pasadena  and  Pasadena,  are  hereby  appointed,  by  virtue  of 
their  office  and  during  their  incumbency,  a  BOARD  OF  EN- 
GINEERS, with  the  right  in  each  of  said  cities  at  any  time 
to  appoint  an  engineer  to  act  temporarily  or  permanently  on 
said  Board  in  place  of  its  City  Engineer.  In  the  event  that 
there  is  a  change  made  in  the  office  of  City  Engineer  of  either 
of  the  cities,  then  the  successor  in  office  shall  become  a  niem- 

49 


ber  of  said  Board  of  Engineers  in  place  of  his  predecessor,  or, 
if  any  of  the  cities  shall  have  appointed  an  engineer  on  said 
Board  of  Engineers  in  place  of  their  City  Engineer,  then,  if 
said  Engineer  so  appointed  fails,  or  refuses  to  act  on  said 
Board  for  a  period  of  more  than  ten  (10)  days,  or  if  there  is  a 
vacancy  in  the  office  of  City  Engineer  of  either  city  for  a  period 
of  more  than  ten  (10)  days,  and  no  one  is  appointed  to  act  on 
said  Board  to  fill  said  vacancy,  or  if  any  City  Engineer  fails, 
or  refuses  to  act  for  a  period  of  more  than  ten  (10)  days,  then 
the  remaining  member  or  members  of  said  Board  may  proceed 
with  the  business  of  the  Board  without  the  presence  or  vote 
of  said  member,  or  members  so  absent.  Said  Board  shall  act 
only  by  unanimous  vote,  subject  to  the  provisions  of  paragraph 
"SIXTH"  hereof. 

Said  Board  of  Engineers  shall  forthwith  proceed  to  pre- 
pare plans  and  specifications  for  an  outfall  sewer  and  disposal 
works  complete,  said  outfall  sewer  to  connect  with  said  Gar- 
field Avenue  main,  and  shall  make  a  report,  as  soon  as  possible, 
showing  the  available  locations  for  disposal  w^orks.  Copies  of 
said  plans  and  specifications  and  report  shall  be  filed  in  the 
office  of  the  City  Clerk  of  each  of  the  parties  hereto. 

FIFTH  :  Upon  the  preparation  of  said  plans  and  speci- 
fications and  presentation  of  said  report  showing  various  avail- 
able locations  for  disposal  works,  and  the  filing  thereof  as 
above  provided,  and  on  the  filing  of  the  findings  as  to  the 
apportionment  of  the  cost  thereof,  as  hereinafter  provided, 
all  of  which  must  be  done  within  six  (6)  months  after  the 
execution  of  this  agreement,  the  legislative  body  of  the  City  of 
Alhambra  shall  select  one  (1)  of  said  available  sites  and  shall, 
as  soon  as  practicable,  propose  a  bond  issue  to  the  people  of 
said  City  for  the  purpose  of  raising  sufficient  funds  to  pay 
said  City's  share  of  the  cost  of  said  outfall  sewer  and  disposal 
works,  and  of  the  site  so  selected,  and  shall  forthwith  proceed 
to  call  and  hold  a  special  election  for  the  purpose  of  author- 
izing said  issue  of  bonds,  PROV^IDED,  that  failure  to  hold 
said  election  at  an  early  date,  or  the  failure  of  said  bond  elec- 
tion to  carry,  shall  not  in  any  wise  afifect  the  validity  of  this 
contract,  and  as  soon  as  funds  are  available  in  the  treasury 
of  Alhambra  for  the  purpose  of  paying  its  share  of  the  cost  of 
acquiring   said   site,   and   necessary   rights   of   way,   and   con- 

50 


structing  said  outfall  sewer  and  disposal  works,  then  the  City 
of  Alhambra  shall  acquire,  by  purchase  or  condemnation  (the 
expense  to  be  borne  as  hereinafter  provided),  the  site  selected 
as  aforesaid,  and  shall  advertise  for  bids  for  the  construction 
and  installation  of  said  outfall  sewer  and  disposal  works,  and 
shall  proceed  to  let  said  contract  and  construct  said  work,  all 
under  and  in  accordance  with  the  terms  of  an  Act  of  the  Legis- 
lature of  the  State  of  California,  entitled  :  '"An  Act  Author- 
izing Municipal  Corporations  to  permit  other  Municipal  Corp- 
orations to  construct  and  maintain  Sewers,  Water-Mains  and 
other  Conduits  therein,  also  to  construct  and  maintain  Sewers. 
^^'ater-Mains  and  other  Conduits  for  their  joint  benefit,  and 
at  their  joint  expense,  and  to  make  and  enter  into  Contracts 
for  said  purposes."  approved  Alarch  22nd.  1909.  as  amended 
by  amendment  approved  March  7th.  1911,  and  as  now  in  force, 
and  Alhambra  is  hereby  designated  as  the  City  to  do  said 
things. 

SIXTH  :  If  at  any  time  any  disagreement  should  arise 
between  the  parties  hereto  in  regard  to  the  interpretation  of 
this  contract,  or  in  the  doing  of  any  of  the  things  provided 
therein  to  be  done,  then  the  Board  of  Engineers,  or  the  govern- 
ing bodies,  of  the  parties  thereto,  as  the  case  may  be.  shall,  if 
they  are  unable  to  agree,  each  appoint  an  arbitrator  and  the 
United  States  Engineer  at  San  Pedro,  and  the  Consulting  En- 
gineer of  the  State  Board  of  Health  shall,  with  the  three  (3) 
so  appointed,  act  as  a  BOARD  OF  ARBITRATION ;  but  in 
the  event  that  either  of  the  two  officers  above  designated  shall 
refuse,  or  be  unable  to  act,  their  place  or  places  on  the  said 
Board  shall  be  filled  by  Engineers  to  be  appointed  by  the 
Senior  Judge  of  the  United  States  District  Court  for  the 
Southern  District  of  California,  Southern  Division.  The  de- 
cision of  said  Board  of  Arbitration,  or  a  majority  thereof,  sliall 
be  final  and  binding. 

SEVENTH :  All  payments  of  every  description  to  be 
made  under  this  contract,  or  under  any  contract  entered  into 
pursuant  hereto,  or  pursuant  to  any  judgment,  decree  or  order 
of  court,  or  Board  of  Arbitration,  or  reference  or  cost  and  ex- 
pense of  litigation  arising  hereunder,  shall,  except  as  herein 
otherwise  expressly  provided,  be  made  in  a  proportion  to  be 
determined  upon  by  the  Board  of  engineers  according  to  the 

51 


benefits  to  be  derived  by  the  parties  from  the  use  of  the  said 
outfall  sewer  and  disposal  works,  and  the  findings  of  said 
Board  in  the  -matter  shall  be  filed  in  writing  with  the  City 
Clerk  of  each  of  the  parties  hereto,  and  shall  include  a  definite 
scheme  or  plan  by  which  at  certain  stated  intervals  the  pro- 
portionate share  of  all  sums  needed  for  the  operation,  repair, 
renewal  or  maintenance  of  said  work  provided  herein  to  be 
done,  shall  be  adjusted  according  to  the  benefits  derived  by 
the  parties  hereto  at  said  stated  times,  and  each  city  shall  be 
liable  only  for  the  proportion  provided  to  be  paid  by  it,  and 
each  city  hereby  obligates  itself  to  pay  said  proportion 
promptly. 

EIGHTH  :  The  parties  shall,  until  a  different  scheme  of 
sewage  disposal  than  that  recited  herein  is  agreed  upon  by 
them,  keep  and  maintain  said  outfall  sewer  and  disposal  works 
to  be  constructed  under  the  system  proposed  hereunder,  in 
good  order  and  repair,  and  shall  cause  the  same  to  be  oper- 
ated for  the  disposal  of  sewage  of  the  parties  hereto,  and  such 
other  parties  as  may  be  able  to  agree  with  the  parties  hereto, 
upon  terms  for  the  use  of  same. 

XIXTH:  Pasadena  further  agrees  to  discontinue  en- 
tirely the  use  of  its  City  Farm  for  sew'age  disposal  as  soon  as 
practicable  after  the  outfall  sewer  and  disposal  works  pro- 
vided for  herein  shall  be  constructed  and  already  for  use,  and 
further  agrees  to  divert  at  once,  upon  the  completion  of  said 
outfall  sewer  and  disposal  works,  at  least  one-third  (Ys)  of 
the  sewage  then  discharged  on  said  Farm  to  said  outfall  sew^er, 
and  to  divert  without  one  ( 1 )  year  thereafter,  one-half  of  the 
remaining  two-thirds  (%)  of  the  said  sewage,  and  to  divert 
within  one  (T)  year  thereafter  the  entire  remainder  of  said 
sewage  to  said  outfall  sewer  and  works,  due  allowance  to  be 
made  for  the  time  during  which  Pasadena  may  be  prevented 
by  injunction  or  other  causes  not  its  owai  fault,  from  using 
said  outfall  sewer  after  the  commencing  of  said  period,  PRO- 
\"IDED  that  the  delayed  user  of  said  sewer  shall  not  afifect 
the  payment  of  the  proportionate  shares,  but  said  payments 
shall  be  made  in  the  same  amount  as  if  Pasadena  and  South 
Pasadena  were  to  divert  their  entire  amount  of  sewage  to 
said  sewer  as  soon  as  said  sewer  was  completed. 

52 


TX  WITNESS  WHEREOF,  the  City  of  Pasadena  has 
caused  this  contract  to  be  executed  in  triplicate  on  the  18th 
day  of  December.  1914,  by  the  Chairman  of  its  Commission, 
and  its  corporate  seal  to  be  affixed  by  its  City  Clerk,  both 
thereunto  duly  authorized  by  Resolution  No.  3657  of  said  City ; 
and  the 

City  of  South  Pasadena  has  caused  this  contract  to  1),' 
executed  in  triplicate  on  the  14th  day  of  December,  1914,  by 
the  President  of  its  Board  of  Trustees,  and  its  corporate  sea! 
to  be  affixed  by  its  City  Clerk,  both  thereunto  duly  authorized 
by  Resolution  No.  771  of  said  City;  and  the 

City  of  Alhambra  has  caused  this  contract  to  be  executed 
in  triplicate  on  the  14th  day  of  January,  1915,  by  the  President 
of  its  Board  of  Trustees,  and  its  corporate  seal  to  be  affixed 
by  its  City  Clerk,  both  thereunto  duly  authorized  by  C)rdi- 
nance  No.  838  of  said  City. 

CITY  OF  PASADENA. 
By       R.  L.  Metcalf. 
(SEAL)  Chairman  of  its  Commission. 

ATTEST: 

Heman  Dyer, 
Clerk  of  the  City  of  Pasadena. 

CITY  OF  SOUTH  PASADENA. 
By      Ernest  V.  Sutton, 
(SEAL)  President  of  its  Board  of  Trustees. 

ATTEST : 

B.  V.  Garwood, 
Clerk  of  the  City  of  South  Pasadena. 

CITY  OF  ALHAMBRA, 
By      J.  B.  Sexton. 
(SEAL)  President  of  its  Board  of  Trustees. 

ATTEST: 

Walter  M.  Eddy, 
Clerk  of  the  City  of  Alhambra. 

Approved  as  to  form  : 

John  Munger, 
City  Attorney  of  the  City  of  Pasadena. 

53 


ANALYSES  OF  PASADENA'S  SEWAGE 
(Parts  Per  Million) 

From  July  22,  1915,  to  October  7,  1915 


Solids 

Solids 

Nitro-         Flow          Xitro- 

Nitrogen 

Nitrogen  as 

Total 

in 

in  Sus- 

gen as      in  cu.ft.      gen  as 

as  Free 

Albunimoid 

Chlor- 

Date 

Time 

Solids 

Solution 

pension 

Nitrates     per  Hr.     Nitrates 

Ammonia 

Amnion 

ine 

10-7-15 

1 

a.m. 

720 

548 

172 

None     1000     None 

37.5 

6.25 

109.92 

10-7-15 

1 

a.m. 

644 

510 

134 

37.5 

5.00 

88.65 

10-7-15 

2 

a.m. 

544 

474 

70 

780 

37.5 

4.00 

52.19 

10-7-15 

2 

a.m. 

656 

554 

102 

37.5 

5.00 

127.65 

9.23-15 

3 

a.m. 

460 

426 

34 

640 

30.0 

2.00 

180.84 

9-23-15 

3 

a.m. 

670 

590 

80 

40.0 

7.40 

248.22 

9-23-15 

4 

a.m. 

420 

378 

42 

610 

62.5 

2.40 

159.57 

9-23-15 

4 

a.m. 

596 

542 

54 

40.4 

5.40 

265.95 

9-16-15 

5 

a.m. 

1024 

390 

634 

720 

20.0 

18.00 

42.56 

9-16-15 

5 

a.m. 

600 

520 

80 

30.0 

2.40 

120.56 

9-16-15 

6 

a.m. 

400 

350 

50 

620 

22.5 

2.20 

42.56 

9-16-15 

6 

a.m. 

510 

480 

30 

•' 

25.0 

2.00 

106.38 

8-26-15 

7 

a.m. 

424 

390 

34 

1520 

20.0 

2.20 

67.37 

8-26-15 

7 

a.m 

526 

524 

2 

30.0 

2.00 

112.05 

8-26-15 

8 

a.m. 

382 

372 

10 

1400 

20.0 

1.40 

53.89 

8-26-15 

8 

a.m. 

478 

470 

8 

" 

25.0 

2.00 

97.16 

7-29-15 

9 

a.m. 

460 

364 

96 

1300 

20.0 

6.00 

60.20 

7-29-15 

9 

a.m. 

480 

450 

30 

" 

20.0 

3.00 

106.38 

7-22-15 

10 

a.m. 

1390 

612 

778 

1260 

50.0 

16.00 

151.90 

7-22-15 

10 

a.m. 

714 

578 

136 

50.0 

10.00 

106.38 

8-19-15 

11 

a.m. 

1156 

824 

332 

1070 

00.0_ 

69.00 

230.49 

8-19-15 

11 

a.m. 

872 

654 

218 

56.25 

9.50 

145.39 

9-2-15 

Noon 

1042 

336 

706 

1480 

00.0 

50.00 

217.72 

9-2-15 

Noon 

766 

630 

136 

00.0 

49.00 

129.07 

9-2-15 

1 

p.m. 

920 

606 

314 

1150 

22.5 

12.00 

80.84 

9-2-15 

1 

p.m. 

844 

738 

106 

" 

34.37 

6.00 

154.60 

9-16-15 

2 

p.m. 

964 

630 

334 

1260 

12.50 

7.00 

138.29 

9-16-15 

2 

p.m. 

780 

626 

154 

"                         " 

31.25 

5.00 

95.74 

10-7-15 

3 

p.m. 

676 

546 

130 

1400 

7.50 

40.00 

106.38 

10-7-15 

3 

p.m. 

720 

604 

116 

28.125 

3.75 

106.38 

8-19-15 

4 

p.m. 

896 

530 

366 

1040 

25.0 

9.40 

79.40 

8-19-15 

4 

p.m. 

680 

604 

76 

25.0 

4.50 

97.80 

8-12-15 

5 

p.m. 

570 

376 

194 

1070 

00.0 

5.0 

35.40 

8-12-15 

5 

p.m. 

518 

418 

100 

"                         " 

25.0 

3.50 

53.19 

8-12-15 

6 

p.m. 

462 

334 

128 

960 

10.0 

3.0 

46.09 

8-12-15 

6 

p.m. 

492 

400 

92 

" 

12.5 

3.0 

42.55 

8-19-15 

7 

p.m. 

2010 

526 

1484 

900 

25.0 

25.0 

74.46 

8-19-15 

7 

p.m. 

610 

544 

66 

•'                         " 

25.0 

4.5 

78.01 

8-19-15 

8 

p.m. 

552 

434 

118 

970 

18.75 

5.5 

63.83 

8-19-15 

8 

p.m. 

554 

526 

28 

" 

25.00 

3.0 

70.92 

8-26-15 

9 

p.m. 

644 

426 

218 

990      64 

13.75 

6.0 

55.34 

8-26-15 

9 

p.m. 

578 

490 

88 

4. 

21.875 

3.0 

75.88 

8-26-15 

10 

p.m. 

574 

426 

148 

990     None 

20.0 

5.0 

56.73 

8-26-15 

10 

p.m. 

536 

" 

18.75 

3.5 

67.37 

9-2-15 

11 

p.m. 

880 

482 

398 

1330 

00.0 

49.0 

87.23 

9-2-15 

11 

p.m. 

570 

530 

40 

■' 

00.0 

31.2 

85.10 

9-2-15 

Midnight 

1632 

626 

1006 

1220 

22.5 

27.5 

75.88 

9-2-15 

Midnight 

586 

566 

20 

"                         " 

25.0 

3.6 

90.06 

FRANK  E.  MARKS, 

City   Chemist,   Pasadena,   Calif. 


54 


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